I use mostly use all freeware. I guess I will name a few:
CCleaner - Great freeware program that cleans your computer out, on some old computers sometimes you can get a Gb or 2 with the cleaner. It also has a Add/Remove Program utility, and a registry cleaner.
AVG Free Anti-Virus by Grisoft - Great free anti-virus, and I love it very much. I have been using it for about 2 years and it is one great AV. I would recommend you switching to it as I have seen dozens of computers with McAfee and McAfee had did nothing to help the infections. The only way McAfee usually gets around is just being pre-put into a computer during manufacturing
Ad-Aware 2007 Personal by Lavasoft - I have also used the free version of this software for about a year or two. It is a great anti-spyware application and it is used even by my school. I also use it in fixes on client PC's.
Spyware Blaster by JavaCool - It is a great program and it works silently with Mozilla Firefox and Internet Explorer protecting your computer from infection and other such things. Just update it, enable all the protections, and you're good to go.
Here are a few that I can think off of the top of my head but, there are more. As I have said above, I would recommend from my own personal professional experience, do NOT use McAfee use at all.