If you're not looking for a monitor with the rig here's what I would do (all from newegg):
LITE-ON 18X DVD±R DVD Burner With 12X DVD-RAM Write Black IDE Model LH-18A1P-186 - Retail $32
COOLER MASTER Mystique RC-632-KWN1-GP Black Aluminum ATX Mid Tower Computer Case - Retail $130
Western Digital Raptor WD740ADFD 74GB 10,000 RPM Serial ATA150 Hard Drive - OEM $160
Western Digital Caviar SE WD2500JS 250GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM $70
PNY VCG8800XXPB GeForce 8800GTX 768MB GDDR3 PCI Express x16 Video Card - Retail $550
Creative Sound Blaster X-Fi XtremeGamer 70SB073A00000 7.1 Channels PCI Interface Sound Card - Retail $90
Thermaltake toughpower W0105RU ATX12V / EPS12V 700W Power Supply - Retail $166
CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400C4 - Retail $135
EVGA 122-CK-NF68-AR LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard - Retail $250
Intel Core 2 Duo E6600 Conroe 2.4GHz LGA 775 Processor Model BX80557E6600 - Retail $318
Total before shipping and mailin rebates: $2044,
maybe spend 50 dollars more and get the BFG graphics card. Their customer service policy has been, in my experience, "if you have a problem, we'll send you a new one." Drop 60 dollars more on a Zalman 9700 fan and use the automatic 20% overclocking nTune feature that comes with the 680i chipset. You're then running a near top of the line machine for any game in any resolution under 1600 x 1200 (higher resolutions would require 2 8800 GTXs, which would require a lot more cooling and power, and probably an EX6800 to prevent CPU bottlenecking). The sound card is definitely the cheapest of the X-Fi, I'm not sure what the performance difference is between the XtremeGamer and the XtremeMusic ($130 from NE). Creative is a solid gaming company though; I'd trust the XtremeGamer to still be an impressive card.