If you haven't read Part 1 of my guide,
please do this first.
Here are a few more free software programs which could be useful to you:
Photoshop
I haven't actually tried this one yet (only because I haven't had time) but Paint.NET looks very promising.
Antivirus
There are quite a few anti virus programs around try one of these ClamAV, Avast, AntiVir or AVG. Well you could simply try all 4 of them since it doesn't cost you anything.
Sound Recording Editing
There are probably better once out there but they will charge you for their software. So try Audacity. It certainly has some nice features and I am sure you will get used to it.
Winzip
There is a complete free software called 7-zip. Can extract from many different formats but sadly can not compress into the same. But hey, it's free.
Sage
Fed up with paying loads of money for sage but then not even use all its features that you pay for. Maybe Turbocashuk can help you to save a little bit of cash. Not sure how good it is since I don't need them.