One of those things I really must find the time to learn about is ClamAV, which is Open Source anti-virus software for UNIX and UNIX-like platforms (i.e. Linux & BSD). There's no file cleaning, but there is real-time scanning and reporting as well as a host of plugins, including one for mail servers.
What's more, there is now the ClamWin Windows port, and (even better) the ClamXav port for OS X.

Here's a nice article about a Linux user getting to grips with a Mac mini. What I liked about it was the techie criticism of Apple's O/S - the spinning beach ball syndrome is apparently due to poor parallelism due to the Mach microkernel.

Check out the useful essential house-keeping tasks for Ubuntu.
Still doesn't help with my ATI card though......