Hey, go to tomshardware, overclock.net or some other site. Much better info. For gpu I would definitely get a HD7970, if not a crossfired 7970. For cpu, it depends. If you are streaming on twitch.tv, than a 8 core fx 8350 will be best. If its just gaming an i5 3570k would be fine, or an i7 3770k. Ram you'll want just some basic 1600 or 1866 (or higher like 2166) 8gb or 16gb ram. Case is your chose but I prefer the fractal design R4.
For budget, you realy don't need to spend $2000. For TF2 only, you only need to use like $1000. For $1000, you can easily get a fx8350 or 8320 (and overclock it), a good 990fx motherboard, 8gb ram, and a 7950 which is overclockable to 7970 speeds. But if you spend more like $1500 you can get some more hard drives and maybe crossfire video cards/sli.
Is it only for tf2?