If you don't know anything about OC'ing, then don't attempt it. Read about it for hours on end - until you think you know about it. Then, read for a few more hours. Then you should be all set.
OC'ing really isn't that hard, it just takes a lot of time and patience.
If you want a little more performance out of your machine, do the following:
Install a firewall (such as Zonealarm (Free)).
Install anti-spyware and anti-adware programs.
Install an anti-virus program
Use tweaked videocard drivers ( www.omegadrivers.net
Keep your machine dust-free
Install any recent Windows updates
That should help you keep your machine running ship-shape.