windows 2k/xp problem

Okay, on my computer I have windows 2000 pro (all the latest patches and service packs). It is on my one and only hard drive, a 120GB Western Digital. I've got a windows xp cd here, and I'm wanting to install it, but my drive is not partitioned. All 120GB are the C:\ drive (and it's NTFS btw). So I'm under the impression that if I want to have both 2000 and XP on the computer, where I can boot to either of them seperately, I'm supposed to have at least one seperate partition for each OS? Is this true? Would having them both on C:\ create problems? If I have to have them on seperate partitions can I partition the drive even though it's already been formatted and used and whatnot? I have 36GB used and I REEEEALLY don't want to erase all my crap just to start all over and have 2 partitions.

So, what are my options?

partion magic can resize a partiton...try it, works good enough, make your 2k partition like 50gigs or so, then another one for xp. then your going ot have to install xp. once this is done 2k will "disappear", but all you have to do is change the boot.ini to see it, or just isntall partition magic's boot loader...

have fun