Partitioning a Hard disk

Hi, just purchased a laptop for university, it only has one drive (C with the whole 40gb allocated to that, I use Windows XP home, and would like to know how to partition it say 20 c: and 20 d:

It's a Hp machine and going through the "Admin tools > Computer management" way to partition doesnt seem to work as all the 40gb has bin allocated to C: so there is no unallocated space, is there any way of partitioning without having to format the machine and start over again?

cheers for the help guys, much appreciated.

 

I think you can do that in Partition Magic.
http://www.powerquest.com/partitionmagic/

 

Cheers for the info, there no other way to do it like for free, I'm a student from the UK, and us students are quite poor unfortunately hehe

 

There is another way to do it for free, but it requires a reinstall of windows.

PS - if you search around on the majorgeeks.com downloads page, you may be able to find a free repartitioning tool. I don't know how well it will work though.