Service Pack 3 Install Error - Not Enough Disk Space

Problem: When attempting to install service pack 3 for Windows XP an error appears stating that there is not enough disk space even though there is plenty of free space on the computer. Error shown below:

"There is not enough disk space on C:\\WINDOWS\$NtServicePackUninstall$ to install Service Pack 3. Setup requires a minimum of 4 additional megabytes of free space or if you also want to archive the files for uninstallation, Setup requires 4 additional megabytes of free space. Free additional space on your hard disk and then try again."

For me the problem showed up in my bootcamp install of Windows XP on my mac.

Solution:You need to add a key to the registry.
- Go to: hkey-local-machine\software\microsoft\windows\currentversion\setup
- Add a new string value named "BootDir" and set the value to C:\

Apparently it was trying to install the update to the recovery partition and not the C: partition.