After a memory leak caused Unity services to stop on a UC machine, TAC recommended applying SP2 because some known memory leak problems were fixed with the update.
Is this Windows 2003 sp2 you speak of or are you referring to the UC 1.2 SR2 release? If anything I would also update UC 1.2 to the SR2 on top of the SP2 for Windows 2003 and get your system as up to date as possible. Both should be safe to apply and fix many a bug. The SR2 for UC 1.2 is available on the Voice Software downloads on CCO.
