If you haven't used Linux in a while, you should give it a second look. Fedora 16 was unleashed on the computing world yesterday.
The latest versions of Fedora, and most modern Linux distributions, have come a long way since the painfully slow and complex installations. Hardware support, especially with the Fedora Project, has been constantly improving. The user interface has greatly improved over time and there is a nice package of productivity tools included (read: M$ Office alternative).
Many of the apps included don't have the same polish as in Mac OS or Windows, but for free, you get an amazing operating system. It is also a secure alternative to Windows and Mac OS, just based on the quantity of malware written for Linux, it's virtually non-existent.
Download it today and give it a try. It'll run on new and old hardware alike, 32-bit and 64-bit, and can easily be used in a virtual machine. Have fun!