With wireless networking in Vista there's an issue with lag spikes that occur every 60 seconds as windows searches for wireless networks. This is in the same way as XP used to spike when you used Wireless Zero Config...but it could be fixed by installing third party software. As far as I know there isn't any third parth software for wireless network adapters in Vista yet.
The lags can be incredibly annoying when gaming online or downloading.
Here's a fix for it if anyone's interested. There's a better Beta2 version if you click on "downloads" on the left hand side of the screen.
This little program made online gaming finally better for me!
http://www.codecase.de/vista-anti-lag.html
P.s. It works in both x64 and x86.