This is a good summary site :
http://www.techsupportalert.com/best..._utilities.htm
Check out
Comodo for security software especially a highly rated firewall. Note that I've only just put v3 on one XP box and it seems to slow network that I did not see in v2.
I like
The GIMP for image editing and
Irfanview for viewing. Both can handle RAW images from my camera.
Open Office for not paying more money to Uncle Bill to edit docs and so on. I do find somethings here a pain though.
Generally though I like to go the whole hog and use Linux then even the OS is free. Hardware support is much better as is user experience than used to be the case. I like
OpenSUSE but also have used
Kubuntu (I prefer KDE to Gnome) and
Gentoo. I've dropped the latter for the moment.