Ok so I have a Toshiba laptop that I am getting new memory today for and also "upgrading" from Vista to XP....lol

Well I currently have 2 1gb sticks and after talking to toshiba they said I could run 2 2gb sticks. So thats what I am going to get. I searched online and every once in a while I see a statement like:

My computer didnt recognize my new memory and I had to go into the bio and change it.....or something like that

My question is, once i put the memory into the computer if for some reason my computer dosent detect it, how do I manually make the computer see the memory?

THANKS