Laptop memory is not harder to upgrade, most manufacturer use standard SODIMMS, check your manual of course, the only problem with a lot of laptops is they only have one memory slot accessable meaning if you want to put big memory in you have to open up the laptop to acces the internal one, but its not a big deal either if you are careful, I have done it on mine to upgrade my A64 Laptop to 1 Gb, it had too slots one inside the other accessible, the inside one was populated with a 256Mb stick, meaning that the highest amount of memory I could put it was 1.25Gb with a 1Gb stick (2Gb stick is too expensive.) a 1Gb stick was something like 250 whereas junking the 256 and installing 2 512 was about £100.
If you want to speed up your laptop though upgrade to a 7200rpm hard drive, the difference between that and the standard 4200 pap they put in laptops is astonishing.
As for 2Gb or RAM its all down to what you do with your machine, as a games machine I get by nicely with 1Gb but it won't be long before I need mroe.