Q9400 or the i7-920 ? Please help choose

Well, are you wanting to do much more compared to what you were doing before? Even the Q9400 is a HUGE step up for multi-tasking.

Maybe an i5 would suffice if it was much cheaper? i5 smacks the Q9400 around for nearly the same price (new), due to Core2 production (or lack of).

If I was you I'd go with the 3rd build. A Q9400 would be good to last you a little bit but it'll be ~630 wasted (minus what you sell it for, if you do) by the time you want to upgrade.

I don't use Ebay much so I can't recommend it for PCs and warranties, but Frys is a good company.

I've been running about 75% of that listed above (only ~20 charts, 10 Mozilla, no Excel) for now

I heard a quad-core can run several applications and ~40 windows!!

Based on benchmarking, here are clocking results:
i7-920 at 5424
Q9400 at 3697
P7350 (current laptop) at 1384

http://www.cpubenchmark.net/common_cpus.html

http://www.tomshardware.com/charts/2009-desktop-cpu-cha...

But I'm not sure how "noticeable" a 40% improvement with an i7 will be when these days it's just in terms of a split second, or how this translates overall when multi-tasking, with the main use (80%) by a trading program which isn't even scripted for quad-cores yet (just dual-core), but does interface a LOT with memory & video due to streaming quotes and charts (hence my plan for RAM 8GB+)

i7 is a pretty impressive CPU, it might be overkill for your uses but I really can't say. =/

Due to upgrading issues its hard to recommend a LGA 775 (Core2Quad) build though. Since there is literally no upgrade path.

Are there any other systems you can chose from? Maybe something with AM3 (AMD) or i5?

All things considered a Q9400 will probably suffice for your performance needs.

Agree. I wish there was a way to try the machines first so I'd know!! It is certainly tempting to get an i7 for future-proofing, but one factor is that I may relocate geographically in a few months (and might just sell the PC instead of move it). If upgrading above 4GB of RAM on a laptop weren't so ridiculously expensive, that would be the choice, but a desktop is the better value.

Plus, I have in the past typically chosen to buy the "best" tech at its peak (currently the i7-920 or 930, for consumers) and usually end up regretting it, as prices drop so quickly.

I think a refurbished AMD Phenom II X4 955 or 965 would be a good compromise for my current needs, as those do usually have two 16x slots for video cards, but I haven't seen any on the market... if you see any, please let me know!! As for new 965 or i5, the prices are so close to the i7, I would just go for the i7. Btw, I've noticed that the i7-920 refurb stock out there is starting to run out as well, as Intel has switched to the i7-930.

I would consider a system with an AMD propus 620 or 630 quad. Those are a bit cheaper than any of the processors you mentioned and will open up the upgrade path to AMD's 6 core cpu to be release later, as long as the motherboard its built with supports it. The same applies to the Intel build you mentioned.

I'm not a fan of buying prebuilt systems but if you must, consider this:

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

Its doubtful you can depend on upgrading the cpu at all if you buy prebuilt. If you don't know how to build a pc, its easy and you can get help here to do it if you buy the components yourself and you can choose your components for better upgrade options & reliability.

If you buy any prebuilt system, plan to use it as a spare or to sell VERY cheap after you buy a new system...

Propus? Do you mean Athlon? This system seems all right, clocked at 3377 (almost as high as the Q9400), but the graphics card needs to be upgraded, and the PSU is only 300W.

For AMD, unlike Intel, I have little idea which line is upgradeable vs dead-end, but I had thought the Phenom II X4 was the later line. Where does the Athlon II X4 fit into the picture? Are you saying the 6-cores will be on Mobos with this same socket, and how do you know?

Thanks

Yes, the Athlon II is the propus cpu:

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

Thats the issue with about any prebuilt system. Very few are built with upgrades in mind. Usually they are built to sell as is with you paying out the nose to upgrade or buy another system from them in the near future.

I believe the AM3 socket will support the 6 core cpu but not all am3 motherboards. The higher end motherboards usually will support newer processors out of the box or with a BIOS flash update. This is why I suggest to you to ask for help to make a list of parts to buy and build this thing yourself so you know what is in your machine and you know what its capabilities are with upgrading and repairs.

Tbh everyone should know something about the workings of a pc if you use them. There's a new level of a sense of ownership when you build it yourself...

+1 Athlon II X4. Great value and should do fine considering your laptop is almost up to the task. Its not quite as strong as the Q9400 but it's still a big upgrade from your laptop's CPU.

Stick with an AM3 board (not AM3/AM2+) and you'll have a good chance of supporting BD (AMD's future CPU lineup) in the future.