I just upgraded to 2 gigs this weekend, and let me tell you, it sure made things on the laptop quite a bit more "snappy" and more responsive. But on the other hand, I can distinguish a frame drop at over 100fps... lmao.
Most of my improvement is in my games and my Adobe software. BF2 loads a lot better and is much smoother in gameplay especially in the larger maps
As far as memory, look on ebay. The memory is called 1GB SIMPLETECH PC3200 SODIMM. OfficeMax just had an INSANE sale (1GB chips for $49.99 each) but that offer is over and all those smart people bought every one they had. You can score these chips on ebay now. I paid $85.00 each including shipping and they are brand new in the package!!