Shoutbox

If you have a Windows XP CD, you can boot from that and when it prompts you, press R to enter recovery mode, this should let you rename the file back (you might need the administrator password to do this).

Alternatively, if you have access to another XP computer, boot into windows on that and insert a blank floppy disk. Then in My Computer, right click the floppy drive, click format and make sure you select "Create an MS-DOS startup disk". You should then be able to boot into DOS mode from that and rename the files.