I have the cash, but I'm saving for a PS4.
You have the cash for a PC but still need to save for a PS4? Would you have bought a 1.2GHz Core2Duo laptop or something?
Anyway, I still think you should buy a PC though since you get way more features, exclusive games, upgradability, customizability, performance, controls, etc.
If you're looking at the same price range as the PS4 ($399) you should be able to build a gaming PC with something like a Pentium G860 (3GHz dual-core), 4 GB RAM and a Radeon HD 7770, which would probably run TF2 at max settings (1080p) at about 100-200 FPS, as well as newer games like BF3 at low settings (1080p) at about 50-60 FPS.
If you go higher than that (which I would recommend) to about $1000 you can easily get a Core i5 4670K (3.4GHz unlocked quad-core), 8GB RAM and a GTX 760 which will run TF2 at max settings (1080p) at at least 300 FPS and any new game at max settings (1080p) with at least 60 FPS.
Both of these machines would also be great for mapmaking, especially the second one since it has a very powerful CPU which will cut down compile times significantly.
I hope this helps.