They released the updated patch today, here is a blurb from microsoft:
"Microsoft re-issued this bulletin on May 28, 2003 to advise on the availability of an updated Windows XP Service Pack 1 patch. This revised patch corrects the performance issues that some customers experienced with the original Windows XP Service Pack 1 patch.
Microsoft originally issued this bulletin on April 16, 2003. Subsequent to that date, Microsoft has received reports of performance problems with the patch from some Windows XP customers. Microsoft has investigated this issue and confirmed that there can be performance problems when the patch is applied to Windows XP Service Pack 1 systems. Microsoft is actively working on a revised patch for Windows XP Service Pack 1 and will re-issue that patch when it has been completed and fully tested. The existing Windows XP SP1 patch does address the security vulnerability discussed in this security bulletin. "
So I think it should be safe to install now, anyone wanna try it out?