Hi James,
I have a D-Link DSL-200 ADSL Modem that connect/power via the USB port. The modem actually comes only with a USB socket and a RJ socket (which you connect to the ADSL/phone line) everything still packed in it's original retail box.
I use the DSL-200 to connect to ADSL via Windows XP for my daughter many years ago (she only use M$ OS) she later upgraded to other model and I keep the DSL-200 until now.
I haven't test the DSL-200 via Linux as I don't have ADSL connection at my place and my understanding is that you may need the right linux driver for this modem to work.
Please contact me off list for the price!
Thanks for the offer, but anything "many years ago" is likely going to be ADSL1 only, and also these things tend to deteriorate over time (capacitors dry out etc). I'm after a new one, just wanted some recommendations on models. Thanks James