I reinstalled Windows XP on a friend's computer. It was nuked with viruses and malware, so I booted with a Ubuntu live CD and used GParted to make a new partition (recovery), move all of their files onto the partition, and erase the primary.
After reinstalling Windows XP, I moved their files back onto the C: drive, and went to disk management to remove the parition. However, the D: partition now has a system flag, even though Windows is installed on the C: drive, with the boot flag and settings, and there is NOTHING on D:
How can I safely remove it (Windows won't let from the GUI) without losing access to the XP install, so I can recover the space from growing the C partition?
Here is a picture of the partitions:

Update: I am informed removing the system partition would ruin the boot loader; can I get an example or walkthrough on how I can reclaim this space? I don't want to be figuring it out "on the fly" when I finally go to fix this problem.