screenshot2 - that's the one I was talking about!
Unfortunately, this registry fix seems not to work in RC1. I suppose they have completely removed the ability of having concurrent sessions?
FYI:
http://www.winsupersite.com/faq/xpsp2.asp
Microsoft removed the concurrent sessions feature from XP SP2, at least temporarily, and current builds do not include this feature. It remains to be seen whether concurrent sessions will be included in XP SP2.