My GF has a netgear router and XP, and her router drops connection frequently and needs to be rebooted. It's usually just because the router is a POS, not because of the client card or OS.

First thing to check is to see if your router has updated firmware available! This is the biggest thing.

Then see if your wireless card has updated drivers.

Make sure you are using the built-in Windows wireless features to connect. If your wireless card came with its own connection utility, disable it and use the windows features instead.

Then make sure your router is using MAC address authentication and WPA encryption; perhaps it's dropping the connection so often because it got pwned and some weenie is torrenting like crazy with it.

Make sure your router's settings are all correct, for instance, it's not set to drop you after 20 minutes of idle time.

If your router has a UPNP check box, try changing it to the other setting (either turning it off or on). I've seen this particular change really help in some cases.

HOWEVER, with all of the above said, there *are* certain rare combinations of access card and router that have troubles under Vista, and I know for a fact they're either fixing it in SP1 or have already released update patches to fix it. You might even be able to look in the KB and find an article about it with a link that lets you download a hotfix. So you can try that.