Sandy,
Sandor's approach works in a highly controlled environment. Sometimes machines of different ages have different versions of the components (they aren't missing, just a version that is too old). SAS does the checking and some, in particular Microsoft's, require reboots. It ma also be that the user had a pending reboot that was unrelated to SAS, in which case you just have to live with it.
We have also found that our use of PGP disk encryption makes it so the tool that SAS provides to pass your credentials to the PC on reboot fails, so the users needs to manually restart the wizard.
Doc Muhlbaier
Duke