Shut up Josh. smile.gif
Before OC'ing, go here
It's a program that will let you know the operating temperatue of your procesor. That's important to monitor.
Go here and download CPU-Z. This will provide information about your mother board, processor, ram and timings. You may need this utility to identify your mobo so you can properly set up mother board monitor.
Once you have baseline speeds and temperatures, you can go ahead and start increasing your FSB speeds a few mHz at a time. I OC through the bios, so when you turn on your comp try hitting F1 or the Delete key (this should be the 1st or 2nd screen you see when you turn on your comp. It should tell you what key you need to press to access the bios.)
If Dell won't let you overclock through the bios, then you'll have to try Kyle's route.
Edit: I wouldn't overclock your graphics card. it's already one of the fastest cards on the market. It's also the most expensive component of your system. Fry it, and you'll be out several hundred dollars.