I'm not entirely sure, but I believe that Grub is only a 'front-end' or user-interface for Lilo. It passes commands to Lilo, based on your selection, therefore if you want to use Grub to boot, you must edit both the 'lilo.conf' and the 'grub.conf' or whatever.
You shouldn't have to reconfigure Lilo to see all of your Windows partitions, only the one that you boot Windows from (your 'C' drive). Since Windows doesn't like being on anything other than the 1st partition on the HD, this is most likely to be '/dev/hda1' or whatever. Once you've booted into Windows, it should be able to see all the other Windows partitions (but not the Linux ones).
If you can boot into Linux, but can't see your Windows partitions, then you need to edit your 'fstab'. There should be a readme/how-to about this, otherwise from within a terminal window, type 'man fstab' (obviously without the quote marks). For a temporary solution:
make a new directory under '/mnt' as 'windows_c' or whatever you want, it should then look like this '/mnt/windows_c'.
From a terminal window type:
'mount vfat /dev/hda1 /mnt/windows_c' (again, without the quotes).
This should allow you to 'see' your 'C' drive. In order to see the others, you must mount them aswell.
If you're running Mandrake, there is a nice and easy way to mount your partitions:
Load 'DrakConf', from this load 'LinuxConf' and select the menu-item of 'File Systems'. Here you should see a complete list of all the partitions available on your hard-drive(s). You can then mount/unmount them. But bewarned, you must already have a 'mount-point' (the directory under '/mnt') for this to work.
If you've got more than 1 hard-disk, and one of them is a scsi, you may have more complications. For example, if your windows partitions are on the scsi disk, the above examples won't work. You will have to read the 'readme's, the 'how-to's and the 'man pages'.
If all else fails:
Use NORTON GHOST (you will find that I *always* suggest this) to back-up your partitions (it _will_ find them) and then start-again. You might want to read: