The 520c has a AAUI plug at the back - for ethernet all you need is a dongle. Internal modems are available but probably fairly slow by modern standards (14.4 or something from memory).

Of course if you have the PCMCIA cage for the 520c you can use PCMCIA cards.

As for printing, the 520c only has a single serial port. Unless you can find a serial-to-USB (not USB-to-serial) adapter you are not going to be able to use the USB be printer.

Hope this helps [] ]'>