Currently there's a checkbox in the top of the Add/Remove Programs window that let you choose if you want to see updates or not, and disabled is it's default state. This is actually very convenient, since the program list would eventually get too big with all those updates, making it difficult to see what was actually installed software and what was just new hotfixes.
The best free anti-virus for Windows is AVG for sure. Too bad Microsoft removed the link to it from the Security Center recommended free anti-virus list. Check http://free.grisoft.com/
for downloading instructions. Avast! is cool, but it does conflict with other software, specially games, that means it's no good for home use at all.