Adding a new memory card

So i bought a new 1mg memory card for my hp pavilion dv2000. It has 2 cards already but their both less than 1 mb. So i replaced one of them and my computer just blued out?? Like became all blue then system recovery came along and it just said error in a blue background.. So i relaced it with the old one.. and it works again.. What should i do now? i mean for it to work? TY!

What did you do to assure that you purchased the correct type of RAM?

Looking at the HP manual for your machine, it appears that the machine uses: DDR RAM at either 667mHz or 533MHz, and can hold up to 1gb per slot

Please provide the complete detail of the Blue Screen Error Warning. That could help us diagnose the problem.