Florin Lazar has some excellent tips posted regarding the new Windows XP SP2 Release Candidate 2 and any current distributed transactions you may have running. There are some changes that you need to be aware for your applications.
Florin also asks for feedback regarding any issues you may find:
I recommend and I encourage you to give a try to this release candidate for XP SP2 on your test systems and send your feedback to the XP SP2 preview newsgroups: http://communities.microsoft.com/newsgroups/default.asp?icp=xpsp2&slcid=us . Thanks!