Two gb is good for anything except high-quality video editing/imaging right now. You should be fine. Just make sure you get another 2x512 mb, not a 1 gb stick.
The ValueRAM series isn't the greatest type of ram... but with 1gb (or 2) it really doesn't matter.... If you find the loading times to be crappy, grab another set of 1gb (must be 2 x 512) and throw it in. Anything more than 2gb is overkill though, and may actually reduce performance a bit.
it will work fine, it's just that if you find the loading times to be a little slow with 2gb... your only other option would be to replace it with another type of ram with tighter timings....