I seem to be in the same boat as Rtyper. I installed 7 yesterday, and internet connected just fine. This morning however, in the Network and Sharing Center, it says that I'm connected to an unidentified public network, but not the internet. I read that this sometimes happens when the computer puts itself to sleep, and to remedy this I turned sleep off and restart the computer. The same problem occurs. Additionally I've turned off firewalls and changed the filesharing encryption to 40 or 56 bit, but to no avail.
Unlike Rtyper, there is no wireless security set up currently, but everything else seems to be very similar if not the same. Any suggestions would be extremely welcome. And please let me know if you need more information on the problem. I'm somewhat new to the PC world, so feel free to talk down to me'
Windows 7 RC Build 7100 32-bit w/dualboot XP