I just tried to setup a dual boot this weekend between linux FC4(Fedora core 4) and windows XP SP2. lets just say after 11 reinstalls of each OS it didn't go so well,lol. I tried every combo i could think of and it just didn't want to work. It might be just me but just make sure you back evrything up.
Wow, what a bummer ...
Anyways, i used Knoppix as a partitioning tool, it also has alot of other nice features, theres a program called Qtparted there which is a GUI partitioner, which sounds pretty good from the ones which run only from CLI ... windows itself can't resize an existing partition, it can only format, create and delete partitions, not particularly helpful seeing as most hard drives have only one big partition taking up the whole space ... anyways yeah, i would recommend Knoppix which has Qtparted