Browsers, in order of preference: Google Chrome, Firefox, anything but IE, IE.
Microsoft Security Essentials is free, and for me, one of the best for virus protection. I think it's one of the few things Microsoft got absolutely right.
One Note is awesome, and the Sticky Notes is something that I cannot live without.
Trillian and AIM are the only two IMers I use, Trillian because I can put more than one IM program under one umbrella and it uses less resources that way. AIM, because I have two accounts, I use my main one for family and friends through Trillian and the other is strictly E related, so I use AIM for that one. Haven't had any issues yet.
Windows 7 is a pretty good set up. I have to admit, I was skeptical, but when I bought my laptop, I fell in love with the OS and paid to upgrade my desktop from Vista to 7. It was worth it.