No, you can't just put the drive in as a slave and access windows 2000 the same way you are accessing windows 7 right now. You are talking about a dual boot system in which you install a boot manager and select which operating system you want to use at startup. That will only work though if windows 2000 was originally running on that machine. You can't take a hard drive from one computer and put it in another computer and just boot it up like normal, you'll have to do a repair install.