I installed NIS2010 Beta today on WIndows7 RC1 (Build 7100) and it installed OK, it also un-installed Norton 360 smoothly.
However, the initial update phase just wouldn't work, the NIS2010 status said "FIX" and it run through the update process but just wouldn't work, it failed on all updates & obvioulsy couldn't process anything. I had read in the known issues post at http://community.norton.com/norton/board/message?board.id=nis2010_pb&thread.id=4 not to run the intelligent updater which I think was a little confusing because I also found this page which has a link to an updater which works for NIS2010, I downloaded it (a 44Mb download) and ran it and it fixed everything. So happy days for me now but just wish I'd known sooner, would have saved an hour of troubleshooting.
Hope this helps