Sidux's primary motto is that it's "Debian Hot and Spicy". Really, I didn't find anything "Hot and Spicy" about it. In fact, the entire desktop experience is calm, soothing, and productive.
I was incredibly happy & surprised to find out how easy it was to setup my new Samsung ML-2510 black & white laser printer. Thanks to Samsung for making the firmware Linux compatible, I literally plugged the printer into the USB port & started printing immediately.
On the other end of the spectrum, there's the call for the ubiquitous "Desktop"--the be-all, end-all interface that everyone, including our grandmothers, can use instead of the hated Windows products.
Older PCs are well suited for building a Linux-based home server. Most current Linux distros ship with the Samba networking software installed, or just a package download away. It's fairly straightforward to configure Samba to work with Windows, Macs, and other Linux systems.