yikes, why not just have her use Avast Free rather than Microsoft's feeble attempt at an AV?
It's a business system -- it wouldn't be right to have her use the free version. Up until 5.0, I've always felt Alwil/Avast was the best option for antivirus -- small footprint, auto updates, it just plain works (other than the "false positive" problem back in December).
With 5.0, I've lost confidence in their software. I've been running 5.0 here, upgraded from 5.0.377 to 5.0.396, and it's still crashing on me. Red "X" on the avast ball, the service has died, no log viewer to speak of, and it DOESN'T communicate properly with Windows Security Center to alert the user that there's a problem.
I can't recommend she (or my many other clients) upgrade at this point.
She needs some kind of antivirus solution -- maybe AVG is the way to go, but I've read good things about the Micro$oft AV, too.
RLW