even still if its in just put the windows boot CD in and load from it instead of loading from hard drive then go to do a fresh XP install and just wipe all partitions off (that will wipe the disk entirely) then install XP freshly. That is of course if it will let you do that and it detects the hard drive.

IDE is a big 24 pin connector on the motherboard.

SATA is a little USB like connector. colour coded either orange or purple or both on the motherboard