Try this for networking Vista and XP

Download this patch from MS and install it on your XP computers....
http://www.microsoft.com/downloads/details.aspx?FamilyId=4F01A31D-EE46...1E-BA11
This will enable Vista to put the XP computers in the right place in the
network map.

Then goto these two sites (and my very grateful thanks to both these guys)
and follow the instructions (3 pages in the first site, don't miss the link
down the bottom).

http://www.computerworld.com/action/article.do?command=viewArticleBasi...axonomy

http://www.hardwarecanucks.com/vista/1008-how-share-root-drive-under-vista.html

After hours of frustration, this worked for me....
Wendy