Unlike catching a cold, you do have a choice when installing software. It really isn't that hard. If the program requires you to install third party software, or a website wants to install some ActiveX plug-in, click no. Then go elsewhere to find what you want. There are options if you take a few extra minutes to look.
Combined with a firewall and anti-virus program, this method would keep your computer quite clean and usable. Far too many people buy a new computer unnecessarily because their old one is so full of cr@p that it is dog slow.
goates