Extreme backups

Hello all,

I'm a college student with a few million documents I really want to save. On top of this, though, I have a modified version of XP sp3, from when I had a buddy who was awesome at computer stuff. n.n I love everything about my current setup, and if it were to ever fail, I would cry---- Cerra is my little buddy.

I know how to back up my files, but I don't think I can back up my actual version of windows while running windows, right? ^.^;

Sadly, my laptop doesn't have a disc drive. It can boot from usb, if that matters.

I have a Freeagent Desk, 1.5 tb. My laptop was originally a windows xp Acer Aspire.

... Help?