The Deaf Sherlock's Safety with your office computer! has some good points in there. It's not too hard to find articles on this subject as well. This will tie in with my next article, Computers in the Trash. Fortunately, most systems can be cleaned up with a little effort and time if you know what to do and use. I've often used these four basic tools to do the major cleanup including Windows' other tools and others as needed;
Spybot - http://www.safer-networking.org/
AdAware - http://www.lavasoft.com/
AVG - http://free.grisoft.com/
CWShredder - http://cwshredder.net/
Then other tools to finish up can be used as needed. I repaired Sherlock's friend's computer awhile ago. He got so frustrated with it that he actually kicked the thing. When I looked at it, the CPU was out of the socket, meaning he kicked it pretty hard. Amazingly, it still powered up after I put the CPU back in. After a few hours of cleaning using the above four and msconfig, we got it mostly cleaned up with a somewhat faster bootup.
I intentionally infected a second computer I have, and it predictably started having strange behaviors. A registry editor and the malware cleaners above plus another tool got it cleaned. Unfortunately, in some cases I've seen, the OS is so hosed, that it requires a format and reinstall.
I'm continually amazed at all the stories I'm hearing about people who go where and do what they aren't supposed to while at work even while the workplace may use access control systems and maybe surveillance utilities. Too many people say yes to anything presented to them without reading them as well as downloading and running anything out there. That's a sure-fire way to a trashed operating system, zombied computers, and badly-infected computers.
Just be careful where you go while at work. Sherlock's not the only techno geek out there...