Build me a $1000-$1200 gaming PC

I've always bought pre-built pc's, but want to build my own this time. It will mostly be used for gaming. I just don't know what parts (Video card, CPU, memory, etc.) would give me the most bang for my buck.

If anyone could list the parts that they would use it would help. That way I could have an idea.

P.S. Is it possible to build a good gaming pc in a shuttle case (microATX)?

Thanks, RC

If I personally had $1,000 - $1,200 for a gaming build, this is what I would buy:

Intel Core 2 Duo E8500 Wolfdale 3.16GHz 6MB L2 Cache LGA 775 65W Dual-Core Processor - Retail
http://www.newegg.com/Product/Prod [...] 6819115036 $189.99

GIGABYTE GA-X48-DS4 LGA 775 Intel X48 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Prod [...] 6813128336 $224.99

G.SKILL PI Black 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Retail
http://www.newegg.com/Product/Prod [...] 6820231209 $59.99

Antec Nine Hundred Black Steel ATX Mid Tower Computer Case - Retail
http://www.buy.com/prod/antec-nine [...] 97579.html $94.99

Corsair TX CMPSU-750TX ATX12V & EPS12V Power Supply - CMPSU-750TX
http://www.buy.com/prod/corsair-75 [...] 78325.html $103.74 -$20.00 MIR

Western Digital Caviar SE16 WD6400AAKS 640GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - OEM
http://www.newegg.com/Product/Prod [...] 6822136218 $74.99

SAPPHIRE 100259-1GL Radeon HD 4870 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
http://www.newegg.com/Product/Prod [...] 6814102801 $299.99

XIGMATEK HDT-S1283 120mm Rifle CPU Cooler - Retail
http://www.newegg.com/Product/Prod [...] 6835233003 $31.99 -$10.00 MIR

XIGMATEK ACK-I7751 Retention Bracket - Retail
http://www.newegg.com/Product/Prod [...] 6835233019 $8.49

SAMSUNG Black 22X DVD+R 22X DVD-R 16X DVD-ROM 2MB Cache SATA 22X DVD±R DVD Burner with LightScribe - OEM
http://www.newegg.com/Product/Prod [...] 6827151173 $27.99

Total - $1,117.15 - $30.00 MIR's = $1,087.15

What resolution will you be gaming at? The above build assumes 24" and leaves the option for adding another 4870 in full-speed crossfire in the future. You could also go with a P45 chipset motherboard and 4870x2 if you don't think you'll want to do crossfire.

GIGABYTE GA-EP45-UD3P LGA 775 Intel P45 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Prod [...] ec48cbc426 $136.99 -$20.00 MIR

VisionTek 900250 Radeon HD 4870 X2 2GB 512-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
http://www.newegg.com/Product/Prod [...] 6814129114 $519.99

Don't forget a 64-bit OS.

Microsoft Windows Vista Home Premium SP1 64-bit English for System Builders 1pk DSP OEI DVD - OEM
http://www.newegg.com/Product/Prod [...] 6832116488 $99.99

+1 for shortstuff_mt's list.

Try to decide if you're more likely to want that second HD 4870 than not. If yes, it's more cost-effective to get the GA-EP45-UD3P/HD 4870 X2 combination than to do Crossfire. Think of it this way: $225 for the GA-X48-DS4 + $300 for HD 4870 1GB + (guessing) $200 for a second HD 4870 1GB a year from now, you end up paying $725 and you don't even get the full performance for the first year. With the GA-EP45-UD3P/HD 4870 X2 you pay $117+$520 = $637 and get the full speed right away.
Also check out these products:
NZXT Tempest $90
RC-690 $75
Silencer 750W $110 - 15%