Eventually you may since Vista's 64bit edtitions see far better driver support now then XP Pro 64 did. But GParted is still a great free tool for partitioning a drive especially when planning a dual boot. XP's Disk Management tool lacks the ability to resize partitions.
You will have to see files removed from the current primary however. Backing things up is the usual adivce as well as simply seeing more free drive available. Shrinking takes quite a bit longer to see done then simply expanding an existing primary.
For using GParted first get familiar with how that works by reviewing the documentation provided along with screen shots at
http://gparted.sourceforge.net/larry/generalities/gparted.htm
Try a few practice runs to get familiar with how to boot it up to the main gui first. Simply pressing the enter key at each prompt leaving the settings the way they are seen like 1024x768 for a screen resolution and 24bit and not switching to 32bit will see it load right up for you.
The platform independent releases for creating new MS Fat or NTFS type partitions are two in number currently available at
http://sourceforge.net/project/showfiles.php?group_id=115843&package_id=173828
The screen shot below shows the 0.3.3.0 and 0.3.2.0 releases with the 0.3.3.0 seeing the fastest load time when booting from the cd-r seeing the iso image burned to it.
Need a program that reliably burns iso images to disk? You can generally use a cd writer or dvd burner for this with the free version of BurnOn found at
http://www.burnworld.com/burnoncddvd/
Another free burning program often used is the Deep Burner free program found at
http://www.deepburner.com/?r=download BurnOn opens up an IE window for huying the full version after each burn. But I found that good for data dvd backups and other burns as well as seeing GParted images burned to disk.