You would need a third-party program in order to do that, something like PartitionMagic. Make sure your data has been backed up before using any program of this type as things can go wrong.
Are you sure you want only one 80G drive? It's usually better to have at least two for a couple of reasons:
Defragging and searching are faster
If one partition gets a virus, corrupted files or whatever, at least the files on the other partition are somewhat safe.
my pc is compaq hade problems in the passed when i was stupid an didn no nothing a system recovery took place an my c: drive has all my old music,video's,pictures,etc i carnt find them anywere but only through recover my files V 3.98 (5692) but need to pay for that and i dont use credit cards online ever to risky can any one help me please e-mail is firstname.lastname@example.org