Computer account no longer in AD, but computer still thinks it's domain member

Hi all.

I have a computer that was joined to the domain, but somehow, the computer account was removed from Active Directory.  The machine still thinks it's joined to the domain, and its main user still has cached credentials.  What's the easiest way to get this box talking to the domain aggain?  Computer is XP Pro SP3 and domain and forest are in 2003 mode.

Thanks.