Thank you for your warm welcome, Night Hawk!
I am not very savvy in computers and can't say if I had more than one hard drive on my previous machine, but I don't think so. Nevertheless sometimes there is a need to run a deep scan, I guess you can't rely on the fast scan only. I had no problems with earlier versions of avg before they incorporated the rootkit scan with the antivirus and liked it a lot.
I don't know if I understood you right about the ms essential - you mean it's not really antivirus software?
Thanks again, greetings!