USB and Gameport joypads should be supported
For all I can tell USB and gameport joypads should work without problems on Linux or BeOS (/SDL version). I also tested my new USB joypad (Taiwan brand) with the WIN32 version and no problems (WinME, DirectX8.0a and VIA USB) occured and my joypad seems to work just fine.
Maybe some new drivers for your gamepad could solve your problem!
Regards,
Niels Wagenaar