How do you Know?

With a PC and the 300 anti-virus, malware, spyware,firewall,ad-blocking,spam and whatever programs....oh...forgot...and the registry repair programs....how do you know if you have any creepy crawlers running around the hard drive?

You never know for sure.

You mean running around on the mac hd? Mainly because allot of the "bugs" have been written for windows, they target the registry, I'm sure some has come through on the mac, there might be some stuff on your HD. BUT, it won't be active and it really can't cause any harm because OS X doesn't have a registry like windows does.

Sometimes you'll notice that the system is running a bit more sluggish than it was a little while ago. Sometimes you'll get random IE popups when you weren't even using the Internet. In some cases your antivirus program can become disabled for no apparent reason. Sometimes you'll find random new toolbars in your browser that you didn't install.

Most of the time the effects are subtle. The blatantly obvious one are the popups, but even then, most people figure it's part of the browsing experience. The only way to know for sure is by running scans on a regular basis with anti-spyware/adware and anti-virus programs.

NOTE: Moved to Windows forum. Nothing to do with switching or Mac OS.