AntiVirus
AVG Free - Made by Grisoft. AVG is free for single computer home use only. Can scan files from a right click menu, schedule or on demand. Automatically downloads updates each day, you can change the schedule to a time that suits you. Has a realtime scanner and email scanner.
Gmail - Otherwise known as 'Google Email'. Definitely the best web based email. Gives a whopping 2.7GB of storage space which constantly goes up and up. Search function is extremely useful for finding that email you read the other month. Also includes a well designed calendar and has online word processor and spreadsheet programs and a bunch of other useful things. Works well on a mobile phone. Handy tool called Gmail Notifier which sits in the system tray and lets you know when you receive an email. Chat with contacts from inside your email, without having to launch a seperate chat program..
Web Browsing
Mozilla Firefox is my choice of browser. Firefox 2 now has one of the best features, if a web page crashes and shuts down the browser, Firefox will ask if you want to re-open all the tabs that you had open, never lose the page you were on again. Also there a plenty of add-ons available for just about any customisation you could want. Still extremely stable, secure and fast.