pemorej,
NO...not in the sense of what MS would consider a "domain controller" to be. They have many specific processes that are only available in their "Server" OS's, i.e. Active Directory, Exchange Server, IIs, ISA, and others. These are not part of XP Pro and cannot run within the XP Pro environment. You do not see an option to promote the box to a PDC in WinXP Pro do you?
If this is what you are seeking and are small-med in size you might consider SBS. If larger(about 50+) you should be running Server?? already.
rvnguy
"I know everything..I just can't remember it all