External Hard drive... or not

Hey,

I just ordered my 15" MBP and I've been ordering lots of things to go along with it--a sleeve, a mouse, a keyboard, and eventually 2 more gb of ram--and I'm looking for any way to have to buy less stuff.

So my question is, can I program Time Machine to use a partition of my hard drive instead of an external hardrive. I have a 160GB hard drive... say if I were to give it 80GB... would that work?

Thanks.

EDIT: This would also seem more practical. If I have a laptop, I don't want to carry around a hard drive--not that it's heavy, but its just something else to look out for. I just want to have everything tight in my laptop. I hope this is possible

Bump...

this idea doesn't attract anyone?

The idea of using the external drive is to have your backups somewhere OTHER than your internal drive in case of failure. Will Time Machine work using a partition of your internal drive? Yes. What happens if the drive itself fails? You're probably going to lose all your data. Backups do you no good if you can't restore from them. I highly recommend an external drive -- you don't necessarily have to carry it around with you everywhere you go. In fact, if you're using it for backups only it'd probably be better NOT to take it everywhere (IMO).