I guess you need to recover data files, not the operating system or application files, that you can reinstall.
So, if the problem is that the operating system (xp) can't boot but the partition filesystem (ntfs) isn't damaged, then you can use a Linux live cd (like Knoppix or Ubuntu) to boot the computer and access to the partition. This manner, you can copy any files you want to some external hard drive or usb memory stick. I always recommend to have a Knoppix cd nearby (the latest of the versions 5.x boots directly to a graphics environment). After copying your files, you can try to repair the operating system from the install cd with no risk for the data files.
If the filesystem is heavily damaged, then you have to proceed to recovery operations. A first step is to run the "check" function on the ntfs partition from the GParted livecd. However, it usually offers no much for heavily damaged partitions.
Then, there is "photorec", a Linux software able to recover various file types by scanning directly the hard disk space. It comes together with "testdisk", another useful recovery tool. (testdisk is included in the GParted livecd, but not photorec).
The NTFS that I need to retrieve files from under /dev/sda is 54.48 GiB and has 633.52 MiB unused.
This means that the partition was almost full, not good for a system partition. Try to keep at least 15% free.
There is also 7.84 MiB unallocated.
This unallocated is just some empty space due to the rounding of the partition start sector to the "cylinders" of the drive (255 heads x 63 sectors x 512 bytes make these 7.84 MiB).
About your external drive: do you mean 224.53 GiB free in the partition or unallocated disk space?
*** It is highly recommended to backup any important files before doing resize/move operations. ***