We bought a fancy HP Laserjet scanner/printer/faxer/younameit to use as a network printer. The software had to be reinstalled every time, and years later I struggled to get bits of that software off my computers. There are still traces of it because it would not uninstall properly. I have a Canon Pixma now, which is a little slow and not as fine, but I can count on it to always work and to have bare-bones software.

As for computer requirements, I agree with what's recced below, except to say I've got a Geforce 7600 that works fine for high-power gaming, so they probably don't need anything much fancier than that. My computer came as a kit, though, and I've been upgrading it by pieces for a few years, so I sadly can't help.