Stephen,
Once you get the boot disk and get XP up, go to start/run and type in :
scanreg /restore
note space after scanreg and before frontslash, then click OK, that should start the ball rolling to a date ( maybe last 5 ) once you get in DOS. Post back any results and we may can help you further if this doesn't work, but it should.
Also any win98 boot disk should work, but I would go and read all the info at the XP boot disk link above first.