If you don't know how fast your computer is or how much RAM it has, there are several tools that can help you get an inventory of the hardware and software if you have a Windows PC

These are small executable programs that you can download to your machine and run that will give you a list of what is on it.

Belarc Advisor is free
www.belarc.com

TechSurveyor at www.techatlas.org is also free
(This requires signing up for a free "Basic" account with TechAtlas.)