As I've written separately, the networking stack in Windows Vista is significantly different from the networking stack in previous versions of Windows. These differences are discussed, in detail, by experts like Joe Davies of Microsoft.
Like any improvements, the many improvements in networking, in Vista, use more resources - memory and processor - on the host computer. Resources on any peripherally connected computer - or router - will likewise be used more intensively. In testing Vista, Microsoft engineers found out that older routers won't perform as well when used with computers running Vista, as with computers running earlier versions of Windows.
As you integrate your computer running Windows Vista with the rest of your network, you'll find a few challenges with the various computers running other operating systems. Those differences you'll have to work around, with configuration changes.
If you get a new computer running Vista, and your router is a few years old, it's time to replace the router too. Or at least upgrade the firmware - if any is available - obtained from the vendor.
For more discusssion:
- CompatDB.org Forums: Problem with Wireless causing Router Resets
- Mike Salsbury: The Windows Vista Experience
- MSDN: Weird one - Router Death by Vista
- PChuck's Network: AutoTuning In Vista Maybe Not Ready For Prime Time