If you're still using XP managing drive partition size allocations can be a bit of a pain since it doesn't natively support partition resizing like Vista and 7, it also makes managing your XP based test VM a little more awkward too. Generally though many of the options that offer decent quality usually come with a premium if not an eventual nag notice with crippled software features after a certain period of use without payment as is obviously the case with trialware.

Of course you could try the various free Acronis based drive management variants (its still  the exact same highly acclaimed premium drive management software despite the hard drive manufacturer branding over it) from official hard drive manufacturer websites. However you will find that you'll become a little unstuck when it comes to using VM's on that front since in most cases the drives you'll be using are virtual with no hardware signature (unless of course you've assigned a whole physical disk to the VM). The free manufacturer modified versions of Acronis don't allow you to use the Acronis software without one of their hard disks present on the system. 

It looks like home users are now in luck, at one time there were no decent free of hassle options no matter how hard you looked. Stepping up to the plate is EASEUS Partition Master 9.1.1 home edition which is free for home users to download and use. Overall its very easy to use and has a comprehensive set of hard drive management features that don't come as standard with windows  XP (which includes partition resizing). Some people say it doesn't have the slickest interface but for something that’s free I personally reckon it  looks clean, functional and free of clutter without appearing too spartan. It doesn't look or feel too tacky either as many of the trialware alternatives that want your home computer user money come across as being.

As is the case with many of these types of things, if you intend to use it for business or for your corporate IT needs you're going to have to acquire the premium version which is distinguished by the "pro" in its naming convention. You can download the free home version by clicking here.