[LoveTractor]

I do have a Mac triple-booted with OSX Tiger, Vista, and Ubuntu Linux.
Macs use the HFS(Hierarchical File System) file system so they don't need to be defragged like NTFS.
And security-wise the Mac's UNIX kernal is much more secure than Window's...although with Mac's popularity growing, I'll bet the days of virus free Macs will be coming to an end soon.

I do uncheck unneeded stuff under the System Preferences>Internet and Network>Sharing>Services Tab & Firewall Tab & Internet Tabs to isolate my Mac from any network.