Essential Software

If you've got broadband, you'll be wanting some anti virus software and all that malarkey. Here's what I use;
Browser Firefox My favourite browser. Tabbed browsing means you don't have tons of windows open, and it block opoups automatically. And it's free.
Opera A good alternative to Firefox. Also free.
Anti virus CSAV for Windows Not free, but very good. I've not had a virus for about 10 years now. Also, it doesn't pester you all the time, unlike some anti-virus programs.
avast! Home Edition Free. Pieter uses this, and is very happy with it. It has various scan engines included (instant messaging, p2p shield, etc) which can be controlled individually, does NOT add a footer to e-mails (like AVG does) and updates regularly in the background.
AVG Free Advisor Free.
Anti Spyware Ad-Aware SE Personal Free. Doesn't work online, so you are not protected all the time, but if you remember to run it every few weeks you should be OK.
Ewido Not free, but you get a fully working 30 day evaluation. It really is very good though. Recently bought by AVG.
Firewall ZoneAlarm Free, and the business.
Email Pegasus I just prefer it to the Outlook family, and nobidy seems to write viruses to attack it. Also it doesn't load "web bugs" (aka "lazy HTML") unless you tell it to.
RSS Feed Reader
Use this to notification of updates to Catterline Online, plus news, sports, ebay searches, etc delivered straight to your desktop.
FTP SmartFTP Transfering files to and from the server. If you don't know what it's for, you don't need it. If you do know what it's for, you probably already have it )or something similar). I don't know why I bothered, to be honest.
Other cool stuff (not really internet related);
CutePDF "Print" from word, etc to a PDF file.
Paintshop Pro Very good image manipulation program.
Picasa Image management and manipulation from google.
TextPad Text editor.