Make sure your router has wireless turned on, note your SSID and WEP key, and then on your Vista laptop in control panel click on network connections. Check wireless networks (make sure your wireless card is turned on, I spend 2 days trying to figure out why I couldn't find my network and I hadn't pushed the wireless network button on the Acer laptop to turn it on :( ) Right click on the wireless adapter, select properties, click on wireless networks and set the SSID if not there, enter the WEP key and you should then be able to view your shared folders.
Hope this helps.
CJ.