Can i build a computer under $500 w/ 8600 gts

why are you considering the 8600? why not upgrade already?

If you don't need to buy a monitor or operating system you can build a $500 gaming computer with a newer (and better) card. Fill out the following template:
http://www.tomshardware.com/forum/261222-31-build-advic...

Case: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$40 Xigmatek Asgard II
PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$55 Antec Neo Eco 520W
MB: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$80 ASRock 870 Extreme3 R2.0 AM3+ AMD 870 SATA 6Gb/s USB 3.0 ATX
CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$90 AMD Phenom II X4 830 Deneb 2.8GHz Socket AM3 95W Quad-Core OEM ($10 off with code, needs a HSF)
HSF: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$20 COOLER MASTER Hyper TX3 RR-910-HTX3-G1 "Heatpipe Direct Contact" 92mm CPU Cooler
RAM: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$32 PNY Optima 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333 ($13 off with CPU combo)
HDD: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$85 HITACHI HDS721050CLA362 (0F10381) 500GB 7200 RPM 16MB Cache SATA 3.0Gb
ODD: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$17 LG 22X Super-Multi DVD Burner
GFX: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$80 GIGABYTE GV-N440D3-1GI GeForce GT 440 (Fermi) 1GB 128-bit DDR3 PCI Express 2.0 x16

Total, no OS: $499 + S&H (not counting MIR, or combo/specials)

*EDIT* if you don't need a HDD (cannabalize from old build), use the extra $85 to get a 460, 550Ti, or 6850. and a BE proc (the 960T is $35 more, and comes with a HSF)

We don't have much money right now and since we had already bought the 8600 gts, and couldn't use it, thought maybe it would save money to build around it ...thanks for any info

Thanks. All this info is so over my head.. I know I have a good monitor and operating system.. Does that mean like, windows xp?? That's what I have now. I also have disks to my old acer for vista. If that will work. I just need the cheapest build for being able to play fallout's newest game and minecraft etc, that he wants. Today's my husband's last day of work till after Christmas, so I gotta do it as cheap as possible. My other son is wanting a bike too.. So, yeah, cheapest I can build it for for now, the better. I'll upgrade as I can. Thanks for the help in deciding. Y'all are awesome! 

Man, thanks! So what is an hdd? And so I don't need to use my 8600 gts? I can't tell which part is replacing that.. These all just snap in, right? I can just watch you tube to do it ? Thank you!

HDD= Hard Drive.
If you have an older PC, you can use the one from it (same with your DVD drive). You can also use the extra to get a copy of Windows 7 home 64bit (instead of the edit parts).

As for assembly, check out the system builder stickies at the top of the homepage.