at my wits end...please help!

First of all, here's my setup:

Computer A: Windows XP Pro, connected to router wirelessly, internet connection is shared.

Computer B: Windows Vista 32bit, connected to Computer A via a crossover cable.

This was working fine for several weeks (ever since I installed vista) until today. I updated my chipset drivers on Computer A, and now Computer B will not connect to the internet through it. I never could get file sharing to work properly between the two, but I was fine with that as long as I could connect to the internet. When it was working, I had Local Area Connection 1 and 2 on Computer A on a network bridge. I'm a total noob when it comes to networking, I don't even know what a network bridge is or does, but it worked. Now that the comps won't connect anymore, I deleted the bridge. I've tried setting up static ip's...no joy. They are both on the same workgroup. I can't seem to find anything on any forums that is similar to my situation. If you need more specifics, just ask. I will be monitoring this thread intently and impatiently.

Just when I thought I was starting to get a handle on XP networking, Vista comes along and makes things difficult!!