You could always download a Linux live CD and perform repairs with that; but it can be a complex task and you need to be comfortable working with a command line interface.

Otherwise, there's not a lot you can do without an XP CD, unfortunately (short of dropping the drive into another computer and messing with it from there (running chkdsk or something like that)).

If you do get a hold of an XP CD, you might want to try the procedure mentioned <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;307545">here</a>.