If you go to the Palm website under the Support Menu, there' and article there called "How to use your Windows Mobile smartphone as a wireless modem" Its Article ID 14924
I found it under Treo Pro Unlocked heading, if I remember correctly but here's the link...
http://www.palm.com/us/search/suppor...reless%20modem
There it tells you the settings for your Treo Pro and your PC, if using USB, and nowhere does it mention that Vista is required.
The same article also has the instructions to create a Bluetooth Internet Sharing Connection.
If your laptop has come with Vista it will more than likely have Bluetooth capabilities which may work as an alternate option for you.
I have Vista on my lappie and using my Palm Pro as a modem works a treat when I am away from home. Just do need to have a reasonable data plan with your mobile phone tho.
Hope this helps.
AKG