Windows Updates & Viruses

I run a small computer business out of my home. Lately my work has consisted of mainly virus removal and making sure the computer doesn’t get the viruses again. I usually install AVG, Sypbot, and do all the windows updates. Because windows updates take so long and are so repetitive I was wondering if the updates are located on the hard drive somewhere so I can back them up and run them for each system instead of scanning and the installing them. (Like saving them to a disk). I would also appreciate any advice you can give me on AVG or another product I can use to help insure my customers do not get more viruses. Thanks.