For a $2k budget, I would suggest:
Case - Thermaltake Armor or Gigabyte 3D Aurora 570 or Antec 900
Motherboard - Gigabyte P35-DS3R
CPU - E6750 or Q6600
RAM - 2 x 1GB G.Skill DDR2-800 HZs
Graphics - EVGA 8800GTX
Power Supply - Corsair 620HX
Hard drive - Seagate 7200.10 320GB 16mb cache(x2 if you want to RAID them)
Optical Drive - Sony NEC Optiarc DVD Burner
Optional Sound card - Sound Blaster X-Fi XtremeGamer Fatal1ty or X-Fi XtremeGamer 7.1(Cheaper)
Optional aftermarket CPU cooler - Thermalright Ultra-120 Extreme edition(No fan included) or Tuniq 120(Cheaper)
Actually this list, comes under a total of $2000. It's more like $1700+.
I like your suggestions although I think your Soundcard suggestion is a bit overboard, all the Xtreme Gamer series cards really have is X-ram ( which no game really uses so its useless ) and a higher pricetag
Anyways I was wondering Ive seen a lot of people recommend the first case you gave the hyperlink too. I know its a full tower one ( so was my NZXT one the zero which got really good reviews ), however I saw the Terhmaltake at Frys on display and was very dissapointed. It looks really cheap and flimsy, I dunno if I should go with it...
Also why is quad core slower then the dual cores when it comes to gaming tests?