Well FIRST... you do not need that Killer Xeno network card. Tomshardware did review of that card versus the onboard network on a gigabyte motherboard and ther was no difference. So take the money that card costs, and bump up to a 6gb RAM KIT!
As to your concerns abotu the mobo and CPU, I'm not sure what you're concerned about? That's a great setup, it's actually overkill for creating presentations.
If you're not a gamer, are you overclocking? Why the liquid cooling system?
You don't need to overclock for PP and excel.
Actually, you could use a netbook for those things, and it would be portable for giving the presentations.
Thank you both. I changed the network card to an upgrade in memory 8gb and the graphics card to a ATI 5830 1gb. I laid out the system to be current and easy to upgrade over time. I hope I accomplished this?
I'll be honest, not sure why lowrider wants you to have more RAM, 4gb should be more than plenty for all you do including gaming.
If you are not hard core gaming I would drop the liquid cooling - no need for anything beyond the stock cooler that comes with processor unless you are OCing
Change the RAM to 4gb 1600mhz CL7 G Skill as it is great RAM.
Drop the case down to a HAF 922, no real reason to spend more on the 932
In fact, nothing you have mentioned aside from some gaming requires anything more than a good notebook, which means in reality, gaming is the biggest performance hog of your Desktop. If that is the case then I would:
Drop the Hexcore processor to a x4 955 as you need no more than 4 cores for gaming.
Drop the HDD to a Samsung Spinpoint F3 1TB, it is only 3gb/s, but in reality for an HDD the 6gb/s offers nothing significant, it is mainly for if you get a Solid State Drive in the future.
The motherboard is probably overkill - you are not a hardcore gamer and therefore will you ever be using Crossfire? There are cheaper boards that will offer you USB 3 and SATA 6gb/s
With the money saved on these adjustments you could get a 5850 and still probably have spare money.