I did some internal testing of this solution.
Testing setup was 2008 domain with Netgear AP. Clients was windows XP /Windows 7
Windows XP had a large limitation that the network can authenticate against the domain computer account, but if you want to have user authentication as well, the re-authentication from computer to user happens during the logon process. This breaks roaming user profiles + scripts as the network connection is lost then reconnected. I believe Vista has this same limitation. A Microsoft page said this was by design and not going to be resolved. (lost the link i'm afraid)
Windows 7 resolves this issue by re authenticating before the normal login process starts, and works well, however as we are not ready to roll out win7 my testing stopped at that point.
The IAS logs are a bit of a mare to follow, but goggling for ias log viewer brings up some shareware software that gives an reasonable hint to the issue in english. It crashes on exit of the program but doesn't seem to do any harm other than that.
