There are numerous causes of this problem, and therefore numerous potential solutions. I spent Friday night, all day Saturday, and half the day Sunday trying to solve the problem on my computer before figuring it out. In the process, I took about 5 pages of handwritten notes from various websites, including this forum. I burned drivers to a CD. And I called both Verizon and Microsoft tech support.
The solution for me was hardware. I have a motherboard with the NForce 4 chipset. Specifically, the Asus P5NSLI. Apparently the motherboard itself cannot handle 4+ gigs of memory plus peripherals. As a result, when I upgraded to Windows 7 64 bit, I lost internet connectivity. I got the "Unidentified Network" issue, and the IP Configuration error.
To test the solution, I simply removed 2 gigs of memory from my computer, bringing my total down to 2 gigs. Everything worked fine then. Internet was perfect.
Chopping my memory down to 2 gigs is an unacceptable permanent solution, so what I did then was installed Windows 7 32-bit. That has an OS 4-gig memory cap, like Windows XP 32-bit. So now I have 4 gigs of memory back in my computer, it only recognizes 3 gigs, and my internet is fine.
It's still a bummer of a situation. I have a total of 6 gigs of memory for my computer. I only had 4 gigs installed with XP, and my plan was to install the other 2 gigs with Windows 7 64-bit, to get a total of 6. Instead I'm stuck with 3 gigs, and with no possibility of ever adding to that with my current motherboard.
But the problem's solved, and I am left with a gaming rig with a GTX260 graphics card, a Core2Duo E6600, and 3 gigs of ram. It'll last me for another year and a half or so, and at that point I'll buy/design/build a whole new computer. Such is the way with technology. I really can't blame Microsoft on this one because, in my case at the very least, the problem was hardware, not Windows 7.
I hope this is helpful to you in solving your problem.