Nvidia GTX 270 video card

[pevergreen]

270 replacing what?

A processor will make your computer faster. A 270 will give you medium-high graphics setting.

It won't give you 100fps in BFBC2 for example. You still need a fast HDD, CPU and RAM, preferably on the newer architecture (core ix range)

[Husar]

I have a GTX 260, I play BFBC2 on max settings(except anti aliasing on 2x but I almost always set that low) in 1920*1200 and it plays just fine, I don't need 100 fps if my monitor has 60 Hertz...
It may slow down a bit now and then but I haven't noticed any game-breaking slowdowns or so for that matter. In MP that is, haven't tried the SP yet.

Whether you get any great advantages from a GTX 270 depends, as pever hinted, on your current setup, combining it with a Pentium 4 for example would be kinda useless.