I have 2 internal modems. I have did some research on one(a U.S. Robotics 144000 bps modem), but can't seem to download drivers for Linux or Windows, so I have no idea if either of them work. The other modem just has a model number on it.

14.4 eh... Thats pretty damn old dude. No offense or anything, but I would not be surprised if there isn't a linux driver for it. I wouldn't even be surprised if there isn't any Windows 98 drivers for it. Thats fairly old. 14.4 modems were the height of home connectivity back in ... mmm i'd say pre 1996. Thats quite a few years ago. Your probably better off going and dropping and few dollars on a new Hardware based Dial up modem. Make sure that the modem you purchase is compatible with linux by searching the web ahead of time. From my limited knowledge of dial up modems and linux, I'd say go with a 3com (or USR hardware based modem).