Nope no luck...
modprobe fat produces the usual not found error...
Interestingly "modprobe ntfs" works fine! Pity I dont have any NTFS disks in the system (!)
I am beginning to think that my copy of slack doesn't have support for fat compiled as either a module or built into the kernel....
I also noticed something in rc.modules which looks interesting... it was an entry for a modprobe ide-floppy... funny enough this doesn't work when typed into the command line either!
I am going to try and reinstall and then if that doesn't work try a reinstall... if this doesn't work I'll swap to back to Mandrake...
Tangle just out of interest what is your output from lsmod...