Which Mandrake? Back in 7.2, 3 of them. Now, with 8.2 and one little patch, nearly all of them. Do you already have a card? If so what kind? If not: Lucent/Orinoco, or Cisco if you can afford it, but I can't.
I just realized you may have meant wireless cellular modems... offhand I don't think any of them are supported under Linux as they're all win-modems, reliant on proprietary software to work at all.