MDK 9.0 default installed kernel does support FAT32 partitions i.e. vfat. I have installed this version on more than one PC and its worked the same on each one. I have seen one other post on the subject over at justlinux.com. No idea on what happened or how it was fixed. Might want to post the same question over there. Did you recompile the kernel install anything or change anything with modules etc from the original install?
If this was an existing partition before you installed linux then it would of been auto configured and you should have a /mnt/win_x directory for each existing windows drive. The partition will also be mounted at bootup. If you created the partition after the install then what did you use to create the partition and how did you format it. Also post your fstab file. Are you sure your mounting the correct partition?
As for the winmodem yes 9.0 provides support. You can also check and www.linmodems.org
for additional help. You might want to go to MDK website and download the latest driver. You need to know if it is a hcf or a hsf modem.
I didn't see any support for an apollo? sound card. Are you positive this is correct?
You might want to list all of the your other hardware i.e. motherboard.