http://www.crucial.com/systemscanner/ Use this. It will scan your laptop to see if you can have some mroe RAM.
Most if not all recently made laptops allow for upgradable RAM. I got an extra 1GB RAM chip with my Laptop when I purchased it well over a year ago. It's very easy to insert aswell, and trust me...even the slightest upgrade in RAM can make a huge difference.
Do a Google to get an Instruction page for your model.It should tell you where the RAM is located and its configuration.Some have 1 bank soldered in,some have like 2 x 1gb chips with no spare slots,some have 1 x big chip and 1 spare slot....... This Advent one I'm using had 1 x chip that is easily gotten to,but to get to the other-it needs to be split in half-a major job. The Acer netbook I recently bought has 1 x 1gb soldered chip,and to get to the spare Ram slot is a split in half job.
use the crucial website for that to check if its possible to add a ram in your laptop. You dont have to buy that brand if you dont want to. My 2003 compaq is so slow and i upgraded it with an additional 512 with the 128 fixed ram to make it 640 MB... well, its ok a bit and i found that my laptop can use 3GB of ram...but the ram cost a lot so, i'm happy with 640.