Problem with Vista file sharing?

I'd be grateful if someone could give me some pointers as to what I might be
doing wrong. I have a home network with an XP desktop and XP & Vista
laptops. I can share files & printers both ways between the desktop and the
XP laptop, but whilst the Vista laptop can access files/printers on the other
(XP) machines, it won't allow access to its own files. I'm about to make a
big purchasing decision to replace the XP desktop with a Vista desktop, but
I'm concerned that the laptops might not be able to access its files/printers.