Advent 8215p Restore Advent 8215P Laptop RAM Upgrade Help....?

Advent 8215P Laptop RAM upgrade help....? - advent 8215p restore

I bought this laptop a few weeks ago, and I have in the 1 to 2 GB of RAM upgrade as Vista. However, the site was purchased and the Advent website is completely unnecessary, and I'm not saying anything about the specification of RAM I just know its DDR2, but I'm not sure what the speed. If someone could help me here, so I will not waste money buying the wrong RAM would be useful.