First off, I will mostly be playing Valve games, HL2, Garrys Mod, Team Fortress 2, etc. My current desktop is 5 yrs old. This is a pretty cheap build because I don't need to drop 1000 to experience my games at highest settings. Sometime in the future I want to run N64 emulators.

AMD cpu with 8MB of L3 cache (HOLY SHIT)
http://www.newegg.com/Product/Product.aspx?Item=N82E16819113286

Cooler Master Fan
http://www.amazon.com/gp/product/B003ICXAQS/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=AZCEI3EMXUPTH

ASrock Mobo with usb 3.0
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157323

400W Power supply
http://www.newegg.com/Product/Product.aspx?Item=N82E16817338008

8 gigs of RAM
http://www.amazon.com/gp/product/B004DDI0IE/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

1TB Hitachi drive
http://www.amazon.com/gp/product/B001LDK4FG/ref=ox_sc_act_title_3?ie=UTF8&psc=1&smid=A36CB5VVA8ZISE

CoolerMaster n200 (got a lot of good ratings)
http://www.newegg.com/Product/Product.aspx?Item=N82E16811119274

I can run most games at high settings already. This hardware is a 120% improvement from my current desktop so I will notice a huge jump in performance. Rate it.