I had the same problem unable to get sound AND video working together with MSN 6.x and XP – tried a lot of the fixes on here ( swapping DLL’s etc) but nothing did it for me

So I swap to another client when I want a voice/cam meeting , http://www.eyeballchat.com/ this has worked for all of our family members who where having similar issues to me (you) with XP & msn.
Its also supposed to be able to integrate with MSN so you can pick up whos on that network, but I could never make that bit work, but certainly voice and web cam is no problem

If eyeball can make it work how come MS with all the resources they have let this issue drag on for so long

What hope is there that this issue will be resolved with ver 7 I wonder