Slow moving computer

I've been having a lot of trouble with my computer(Compaq Presario 5152). In 2004 it got infected with spyware and though I got software to remove the spyware the computer has not worked right since. It is extremely slow sometimes. When I have multiple window activated or shutting down the computer, I'd get a message saying it's busy or unresponsive, so I would have to unplug the computer to clear it. I'm thinking about putting the start up disk in the computer that would wipe the hard drive clean and put the computer back to the way it was when I bought it. This would be the second time I've done this. I did this in 04 after the spyware infection. Would this be ok to try?