The only way that you can run XP and use Disk Management to increase the size of a current partition...is to use a 3d-party program., such as Partition Magic. PM (and programs like it) allows users to change the size and create new partitions...without deleting old partitions, programs installed and data on said partitions.
I believe that Vista is a bit different, FWIW.
As for accessing and removing data from the original hard drive...that should be simply a matter of moving, cut & paste, etc., from one drive to another. Right now, you may not have sufficient partition space created on the new drive...but once that is corrected, it's a simple task.
I've never used this (I've had PM since my Win 95 days), but you might want to take a look at GParted Partition Manager - http://gparted.sourceforge.net/