gav,
having a plethora of wireless bits around the house. I have a work around!
you can do it the way you want, but it's a bit hit and miss (due to microsoft's dodgy code) to set up.
Best bet is to download some kind of routing program. Winroute is a good one.
The other alternative is to use a wireless router between the cable modem and both the laptop and the PC.
I use the linksys wireless router which is the 802.11g standard
(
link here)
or if you only want 802.11b (the 11Mbit standard)
try this one
This also means that you dont have to have the desktop turned on when you want to use the laptop, and puts you behind a NAT device which stops quite a few of the nasty's that are floating about.
I used to use netgear wireless stuff but IMHO the linksys stuff is better.
if it gets realy desperate let us know, i've got enough bits round the house to send you a cheap aid parcel.
Simon A