My previous big box computer went FUBAR and I've always thought building my own PC would be fun, so I'm starting to really look into it.
After some self guided instruction, this is what I've come up with for a mid level/mid budget gaming PC with room to upgrade (to Dual SLI, more RAM, etc).
Also, I currently have a 26" HD LCD TV as my monitor I have my 360 and cable hooked up to it as well, so its essentially my all in one media center.
For gaming, start with the best single vga card that you feel comfortable paying for.
The 9800GT is good.
The 4850 is better.
The 4870/GTX260/9800GX2 are comparable, and will run anything out there decently.
Don't plan on upgrading using SLI/Crossfire. You pay more up front on the mobo and psu, knowing that by the time you want an upgrade, you will have to pay top dollar to get a matching card which is obsolete. Plan, instead, on selling the old card, and replacing it with the then next best thing.
A E8400/E8500 will do better in games than a Q6600. Read this: http://www.guru3d.com/article/cpu-scaling-in-games-with...
Build looks good, except for that PSU. Get a better one like a Corsair, Fortron, or Antec. I don't really like 750i motherboards too much but it's not bad if you want to go with nVidia, just make sure it's stable before you send in any rebates . I think it's better to go with a P45 board in that price range with two PCI-E slots and to go with an ATI Radeon that you can crossfire latter .