Would a dedicated graphics card improve performance?

Absolutely you would benefit from video card.
http://www.tomshardware.com/reviews/gaming-graphics-car...

3GB HDDs? Woot? I'm sure you meant 3TBs.

Yes of course it will! But
Because you are not doing any hardware-heavy programs, upgrading to a dedicated graphics card might not be a good idea for you. Unless you are going to play games or do 3D rendering after upgrading your graphics card I don't see any reason why you should upgrade your graphics card.

What card would you recommend and why?

You're absolutely right I should have said 3Tb.3gb would have been amazing when I first started computing (with a 10Mb MFM HD) but today it just doesn't cut the mustard.

If you do not play games, something like a HD6450 might be appropriate, but a gamer card isn't going to do anything for you.
I would suggest considering an alternative to Excel 2003. Office 2003 is no longer supported, and is not going to get any more patches or fixes for security holes. If you don't like the "ribbon" interface of later versions of Office, you might check out LibreOffice (what the actively-developed version of OpenOffice became) instead.
Someone else will need to confirm this, but I believe that for recording, you might benefit from a sound card. Mobo sound is fine for most uses, but for recording you may want a higher SNR than they usually provide. A mid-range product will do, maybe in the $70-$100 range.

I don't think your uses would really see a benefit.

It really is going to come down to whether Corel X6 will leverage a GPU or not. It sounds like not from this post: https://coreldraw.com/forums/t/32410.aspx

Your integrated intel graphics are likely more than enough for what you are doing. Only games, rendering software, and software designed to leverage GPGPU (OpenCL for AMD or CUDA for Nvidia) will actually use the discrete GPU.

^+1, but if you ever do add BluRay, a HD6450 will offload the video decoding from your CPU. That's hardly a big deal with an i7, but if you're running a lot of other things at the same time, it might be worthwhile.

It entirely depends on what you plan on doing, in the future as well, of course. And your budget.

Like others have said, do you plan on playing games?

Where do you feel you need improvement?

Many thanks for all of your well informed comments. I have no plans for blu ray and I'm never likely to be a gamer (co-ordination too poor).

I've tried Open Office but I could find no useful replacement for the "solver" function in Excel. I've also found it impossible to migrate my PST file from Outlook (created and added to over many previous incarnations of MS Office) beyond 2003.

As for budget I'm not really limiting myself but I wouldn't want to spend thousands.

I've thought about a sound card and I'm looking at the ASUS Xonar DX.

I'm not sure that I do need improvement. What prompted my question was my Windows Experience Index where the Graphics and Gaming Graphics indices of 6.6 pulled down the overall index from 7.7 (Processor), 7.8 (Memory) and 7.9 (Primary Hard Disk).

I'm new to Windows 7 (I was originally tying to build the ultimate Windows XP machine before I increased the memory to 8Gb). Is this index really meaningful or does it have no relevance to my usage?

Well, based on that, you really aren't doing anything taxing that will push the system. I actually retract my original statement and don't think a new video card will benefit you.

Windows 7 is a good OS (Not like Vista or... Windows 8!), good luck working on it. About the sound card question, I don't think you need that also, except you really want crispy sound when you hear music. Of course the sound controller in your motherboard is I think decent enough for your usage.

Now on to the WEI stuff. WEI doesn't pretty much affect the performance, I usually leave it out. Yes The intel HD Graphics 4000 Slows you down because they are slower than any modern graphics card, but, we know that you don't need the power of a graphics card so a 6.6 Gaming graphics score would be fine for you.

If you personally want to increase the 6.6, I suggest don't. Why? Because you'll only be wasting your money. But, if you really really want to then OK...

A 7770 should increase that 6.6 to at least 7.5 (I had a 7850 and it scores 7.9)

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Thank you.

I'm not after score for score's sake. If, in your expert opinions, I'd be wasting my cash, then I'll stick with what I've got.

At 65 my hearing has deteriorated to the point where I may not get any benefit from crisper sound.

The score simply shows your lowest value, which would be your gaming/3d graphics, however if you don't play games you can safely ignore this number.

I wouldn't let the lack of a high gaming score bother you one bit, for what you are doing the computer is should be pretty awesome, pretty much the top of the line for what you need the computer for.

(I was gonna suggest an SSD, but I went back and read the OP   )
If you wanted to, you could replace the WD green drives you were considering with a smaller and faster HDD either a Blue's, or a Samsung Spinpoint F3. A terabyte, for me at least, is still an absolutely massive amount of space and I would value a smaller 7200RPM drive over a larger 5400RPM.
But every one has different needs for storage, and you're already booting an SSD so it maybe just splitting hairs either way.

@janschophile - do you like reading books in your spare time? If you do, I would recommend you look into this... Elder Scrolls V: Skyrim
http://www.walmart.com/ip/Elder-Scrolls-V-Skyrim-w-Pre-...

It's an amazingly detailed interactive book that will necessitate a new video card purchase. It's very immersive InMyOpinion

I recently built a new computer with an i5-3570k which also has intel HD4000. I used the integrated for some weeks while saving money for a new video card and I think it worked great and you would need nothing more if you aren't gaming. I actually tested out some games and was successful in playing some slightly older games such as Call of Duty 4, Team Fortress 2, and some others at medium-ish settings. If I can play those games without a video card, then you shouldn't need one for your non-gaming usage.

I've considered 7200 vs 5400 and, with an SSD as system & data disk and the Hard Disks only as data storage, I value capacity over speed. My previous experience of Seagate & Hitachi 7200 drives has not been good whereas my 5400 WD Green drives seem to go on forever. I've had a couple fail within warranty but, since I backup all of my data across a number of PCs on a reasonably frequent basis, I've luckily lost very little. I did consider the WD Black drives but the 1TB size limit (rather than the exhorbitant price) put me off.

The case has the capacity for more smaller drives but, in order to arrive at the capacity that I want I would need to add a SATA card or two and, in my experience that tends to slow everything down. I also worry that more smaller (faster) drives may exceed the capacity of my PSU and/or cause a heat problem.

I did consider a PCIE SSD card (OCZ 240GB RevoDrive 3 X2) but, because it had no XP drivers, I discounted it. I'm sure that it would be faster but I'm not sure that the difference would be noticeable.

I think that I may have the best compromise, in terms of hard drives, for what I want.

Everything I've seen about the revo drives makes them seem reallly hit or miss with whether they even work properly; so don't feel to bad about skipping that. Kinda a Frankenstein tech imo.

Probably a good idea to skip on the 7200RPM if the 6TB storage capacity was an important factor; 6x 7200RPM drives would be a hassle to power and cool for sure. (not to mention organize and manage your stuff between them).