Can't offer remote assistance from to Vista

[guest]

You cannot offer remote assistance from Windows 2003
server to Vista, but it works with XP.

Offering assistance from a remote computer running an earlier version of
Windows won't work because in Vista, Legacy Help and Support Center is
deprecated so Helpsvc.exe and its functionality is no longer available.
When you try to offer Remote Assistance from server 2003, it needs to
instantiate the HelpSvc DCOM object on the Vista machine - however, this
object does not exist.

Please check below article:
Windows Vista & Remote Assistance
http://blogs.technet.com/askperf/archiv ... remote-ass
istance.aspx

If you search the Registry on a Windows Vista machine for that CLSID, it
does not exist. On a Windows 2003 server, that CLSID refers to the Help &
Support Services Service
(HKCR\CLSID\{833E4010-AFF7-4AC3-AAC2-9F24C1457BCE}).

To work around this issue, use one of the following methods:
1) Use a Windows Vista Machine as the Expert machine
2) The Vista machine can send an invitation either via email or by using a
file invitation that the 2003 server can use to connect