Thanks for info, maybe it was a coincidence, but performance is better now and I'm reluctant to reactivate compatibility mode again. I loaded Sonar 7 and it seems to be okay so far.
By the by, I've had Outlook 2007 freeze enough times I took it off and put on Outlook 2003 again, which still freezes sometimes. Never did this in Vista or XP, so maybe there's something else going on.
I am still cautiously optimistic about Windows 7 as things run much faster than they did on Vista (same machine).
Still get motorboating when I use itunes, for just a few seconds at a time, about once every 30 minutes. I use the Delta 66 sound card, but the master volume for that still goes through the windows volume control (I guess that's normal?).