take a look at /etc/fstab. that's a file which as all the information about which drives are mounted. to mount a drive automatically at boot time depends on what file system is has, whether you want all users to have the ability to mount it etc.
to allow non-priviledged users to mount these other drives, you need to add an entry into fstab with the option users added. something along these lines would probably work:
/dev/hdX1 /mnt/some_folder vfat auto,users 0 0
where hdX1 is some partition of yours, and /mnt/some_folder is a folder you want to mount the drive to. the vfat bit refers to the filesystem (in this case fat, but it could be ext3, reiserfs, ntfs (be careful with ntfs - add ro to the column with users in it) etc.). The auto bit would mount it automatically at boot (as opposed to noauto which doesn't) and the users bit allows non-root users to mount it. Hope this helps.