Deleting Partition & Re Installing

I have my original disks that came with my computer and I would like to erase everything completely on the computer since there might be a virus and takes atleast 15 minutes just to load.

Now Ive learned how to delete the main partition and reinstall but that was for something else. Now can I delete the partition and reinstalling xp and windows? Maybe this is a ridiculous question but I want to make sure. Do I have to use a fdisk also? is there another way to do this?

Thanks, I appreciate it.