Do video cards make stuff look pretty and that's it?

It doesn't really improve performance though, right?

Why the heck don't they make a physics processor right now? I'd rather see crap fly around and bullets bouncing off of armor plating rather than just see the individual pores on a CGI character's face! Anyone agree or am I just noobing?

I'm not quite sure what you mean here. Physics and graphics, although dependent on each other for gaming, are both necessary to play any 3d games. For any halfway graphic intensive game you will also need an add in graphics card with a decent chipset (onboard graphics just don't cut it and take up more of the cpu). Without a decent card you'll have a less enjoyable experience if you can even run the game.
There actually is a physics processor from ageia available for gaming, however you still need a decent video card to make use of it and as it costs around $300 and is only compatible with a few games, it's not something I'd ever buy as physics calculations are already currently handled well enough by the cpu and video card. So to answer your question, yes, video cards improve performance.

Yea, a video card improves performance.. more expensive video cards will GENERALLY, give you faster frame rates.

how do u "see" bullets bounce? they just whiz past you, unlike barrells that take a while to fall.

Yea you're being a noob.

people buy gfx cards for many reasons like photoshop and watching tv maybe and doing art. dunno why your making such a fuss about it

I'm unsure as to what, exactly, you're trying to get here. If you knew how most people would respond, then you're clearly trolling. However, some of the responses seem more akin to this flying right over their heads, so I can't be sure. *shrug*

At any rate, If you're trying to make a point on why GPUs have a lot of validity, whilst PPUs don't, you make a good point... but one which only a small number of people seem to get; even hardware enthusiasts can be confused.

And if you were trying to make a point in favor of the PPU... Sorry, then the other responses are pretty much 100% applicable.