I have a 4m Plus myself and it's a real workhorse that I'm sure will live to see 2020. The 500 page paper tray is nice too but it's actually quite hard to find the duplexing unit. only ever found ones for the LJ 5.

I have not had any issues getting both Vista and 7 to print to it short of a bit of tweaking (you don't set the printer up as a network printer but as a printer connected to a TCP port. :?: )

I have managed to get light sensitive photographic paper fed through my printer. You can make some weird images by printing something, exposing it for a minute , then washing off the toner to get a negative of whatever you printed. ;D