networking vista laptop and xp desktop

Hi,

Apologies if this has been covered, but after extensive searching I
can't find any answers.

I'm trying to connect up my new vista laptop to my old xp desktop.

I've used the xp wizard to 'add new computers to network', using a usb
flash drive. When I have first done this everything seemed fine; my
desktop was visible and usable, along with its printer, then after a
restart the desktop computer was no longer visible from the laptop.
'Re-adding' the laptop to the network did't sort things out, however
creating a new network and adding the laptop to it temporarily sorted
things out until restart.

>From research I discovered that both computers had to share the same

work group, which they didn't, so I set these to be the same. On the
first restart of the laptop the desktop had become visible again and I
went to bed thinking things were sorted, but on powering up the next
morning the desktop had once again become invisible to the laptop.

In the nework and sharing center I'm getting the message: "For sharing
and discovery to work properly, make sure the settings in your
firewall program match the following settings", but have no idea how
to to do this. I have a Belkin wireless router which is configured
via a web browser.

Any assistance gratefully received!