you don't mention if you are using current 6.0 or not but whichever, I recommend not using the extensions from Norton or TTPro. I do use NAV7. I think they add and have in the past been less than stellar.
Speed Disk 6 has some great new optimization routines that make it alone welcome, and NUM DD now works with Disk Warrior _and_ doesn't create problems - something that could not be said about NUM 5.03.
Gregory