AVG Scanning

I recently switched from Avast to AVG because Avast was getting a bit heavy on my system. So far so good with AVG, my only concern is the way AVG scans for viruses. I have always used the boot-time option to scan with Avast, I thought it was better to scan before any application was run. I was wondering if scanning for viruses in the middle of a Windows session was as effective? Is there an option similar to Avast's "boot-time" scan with AVG?

 

I forgot to mention I am using AVG free edition.

 

I don't think so, I can't find any such option. You could scan with Windows booted into Safe Mode to achieve a similar effect.