A few weeks ago I switched from "Spy sweeper" to "McAfee Internet Security Suite". Spy sweeper is a good program and is better than most, but I've found that McAfee is even better. It seems to be less intrusive and doesn't annoy you with pop-up questions asking if you want to block or accept something, in addition, it seems to keep all the spyware and viruses off my computer. I've run several scans with the different programs I have and they never find anything. When I had Spy Sweeper it did a great job, but there were occasions when one of my scanners would find something, but with McAfee nothing seems to be able to get on my pc. McAfee is a big program from other security programs, but it stands to reason considering what a great job it does. I would recommend that you have at least 1 GB of RAM though as my old computer has a single core processor and it doesn't even have 1GB or RAM (it has less) and McAfee affected its performance in a negative way. But my new computer has way more RAM than that with 2 GB of RAM with a Duo core processor and it runs just as fast with McAfee and doesn't slow it down at all.
McAfee Internet Security Suite
http://us.mcafee.com/
McAfee Internet Security Suite
http://us.mcafee.com/