Windows 7 is good. :-)
If you press the Start button, then right-click on Computer, then select Properties, you'll get a window with some information. In the section System it tells you what kind of processor you have, how much memory is installed (RAM), and what kind of operating system (System Type). These are the ones we need to see if you need more memory (well you probably do, but that makes it a bit easier to tell you what we're short of).