How can I wipe my hard drive and reformat with an external CD-ROM?

I have an old Inspiron E1505 that I current run XP Media Center on. I'm sick of the garbage associated with Media Center edition, so I have decided to put XP Pro on it instead.

I have a ridiculous amount of fragmented system files from an old operating system left over from a botched reformat, and I want them gone because I'm down to 300 MB of hard drive space.

I know how to do a proper reformat by wiping the hard drive clean and reinstalling from the CD, but my onboard CD-ROM crapped out a while back. When I re-install, I have to use an external CD-ROM and I don't have the option to boot from it because my computer is dated.

Is there any way to delete EVERYTHING off of my hard drive and start over and still get an OS on here without my onboard CD-ROM? I don't want to format and end up with a clean computer and no way to put XP Pro on it. Input? Suggestions? I appreciate it. :)