PSU good enough for GPU?

Yeah it'll be fine.

Try this PSU calculator. http://educations.newegg.com/tool/psucalc/index.html or http://www.corsair.com/psufinder/default.aspx.

^ +1

Do y'all recommend it?

And might as well ask.
What would be a better card to get with this? GTX 260 or HD 4870 1 GB?

Yes I do recommend it. Corsair power supplies are top notch.

I think these 2 cards are very close. Some games might be a bit better with one or the other but overall very close.

What resolution do you game at and how much do you want to spend?

The general rule of thumb is a high quality 500 to 500 watt power supply with sufficient current (amps) on the 12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the 12 volt rail(s) can power a system with two video cards operating in dual mode. There are a few exceptions like the new ATI Radeon HD 4770, 5850, and 5870 cards which use a little less power due to their energy efficiency.

Before purchasing a new psu you will need to decide whether you will evdentually have a pc with one or two video cards.

It's good enough for one GTX 260.

For two you'd want a 750 watter, for three a 1,000 watter. nVidia's certified PSU's are listed here:

http://www.slizone.com/object/slizone_build_psu.html

And if using two and OC'ing, I'd move up to the Corsair HX series or the Antec Signature series

I'm only going to use one.
I have a smaller screen atm so my resolution is 1280x1024.
My screen also uses a VGA adapter so will this slow down the GPU any bit(since I have to use DVI to VGA converter)?