If you are going for an i5 that is around $270 with a mobo and a gtx 670 at lowest is $360. That is already quite a bit of cash unless you already have a monitor, unless you can settle for an i3. Personally I would get an AMD FX 4300 or 6300 because they are cheaper by around 30%.
My gaming build right now is an Athlon II x4 630, radeon 5770, 4gb 1333mhz ram and I can max Skyrim at 45-60fps and Battlefield: Bad Company 2 at around 45-60 as well. It all depends on haw fast you want the games to run, and what games you plan to play.