The last time I installed a distro on a computer having the SIS900 chipset, it wasn't supported. Suse did not support it. Mandrake may not. I do know that Libranet does support this card. Unless you find the drivers, you may have to switch distros or do without the network...but how would you do that?
Check out Libranet if all else fails. Mandrake, however, is my favorite distro.
Cheers...