If you want your full hard drive back, or are ready to go whole hog like Shaun did, there are two steps to recovering your partition.
1. Remove the Windows 7 partition. You can do this simply with the free Easus Partition Manager Home, or GParted. Make sure you have any documents or files you want to save backed up.
2. Edit the bootloader to remove the choice for Windows 7. Windows XP uses a boot.ini file, but Windows Vista and 7 use a new boot resource called Boot Configuration Data. If you use Windows XP and dual boot with Vista or 7, the bootloader is upgraded to the new BCD. There is a command line tool called BCDEdit that you can use to edit the BCD if you’re brave, but there are also GUI editors. I used the free EasyBCD, and simply deleted the entry for Windows 7. Although EasyBCD is meant for Vista, it also runs on XP (because that’s what I have).
You now have your space back!