I never knew for sure until I saw that but I figured you could. What I have found is that if you can get MBAM to install and actually run it will get it cleaned up enough to actually allow an update.
I reccommend AVG or Avast, IMHO both are just as effective as anything you will pay for.
Ive had both and the free ones dont even come close to doing what the ones you pay for will.
on avgs website they pretty much show and tell you this.
Also, avg isnt near as through as norton. I had a computer that had a few nasty virus's and avg couldnt even detect them. (yes it was the most current and updated)
Installed norton and it removed them.