i looked at the man page for mkdosfs and it says that it will either create a fat12 or fat16 filesystem by default if no options are specified to the 'mkdosfs' command (based on what it thinks best), so with the advice from 2damncommon i didnt use any options. so i then went ahead and formatted the floppy with..
i then tested to see if i could transfer a file from linux to xp via the floppy disk, by first mounting the floppy in linux with a commandline i found elsewhere on the net..
'mount -t [fstype] [something] [somewhere]
so i actually typed..
'mount -t vfat /dev/fd0 /mnt/floppy'
next i copied a file to the floppy with..
'cp filename /mnt/floppy'
then i unmounted the floppy with..
i then started XP, and successfully transfered the file from the floppy disk to XP.
thanks for your help guys
(ps, ive given a full account of what worked for me incase any other noobs find it useful too)