I recently upgraded my Thinkpad from 256 megs to 1 G of RAM, and let me tell you, the difference in speed was VERY noticeable. I like to open up a bunch of applications, and the speed at which my pc would access them was almost exponentially increased !

I would highly, HIGHLY recommend surfing www.crucial.com for your memory chips. Mine have been working flawlessly so far !

Also, if you can afford it, MAX OUT your RAM, and you'll never regret it.