I have learned, being a newbie, that External modems are the best. I ended up, after two days of trying to figure out my internal (which is supposedly compatiable-- IF you have access to the drivers, or know how to build modules, and such)

, purchasing a Zoom External Serial Modem, and had it up and going within a few minutes! ( Cost $60.00 @Staples. )
The printer situation- have had a little experience with that as well, if you can find out what type of driver your printer uses, you may be able to substitue from the available list. I had to subsitute a HP deskjet 3320 (hpijs) for my HP deskjet 3520 (hpijs), and adjust the dpi, I do not know if it will work for lexmarks or not.