That seemed to work. It's down to a minor annoyance level of 71megs. In fact, I only had to exclude 1 file:
C:\WINDOWS\system32\wbem\Logs\wbemcore.log
For some reason that log constantly rewrites itself with the error message:
"GetUserDefaultLCID failed, restorting to system verion" [sic]
This caused SAV to constantly scan the thing over and over. I'm not sure what that error is, or why it would be misspelled, but a quick glance through the net turns up a reassuring "you can ignore this"...something to do with service pack 3 on XP pro causing me to go crosseyed. If I've just fallen into a nefarious trap by excluding that file, let me know. Vikram, I owe you a pint-o-booze. Thanks!
p.s. If megs blow up again, I'll be back and screaming.