I made my dual boot between XP and Slack 10.2. I wanted to add a filesystem between the two either with my left over disk space or an extra hard drive. My question is whether I can still mount the fs to my /home directory or if I have to mount it as a seperate drive?

Two things. First, the new filesystem should be FAT32, as that is the only format readily available to both OS's with read/write capability. Second, I have been installing dual boot systems all weekend (my son's teenage friends), and I found it easier to just have it mounted in /data (or something similar), and make a link in ~/home. Seems to be working fine for them. I'm always open for sugestions, though.

I'm curious on how to mount the new filesystem to a directory (as I want to with /home) after Linux has been installed. I've tried doing it before in the past but messed something up to the point that I had to reinstall everything.

When you mount a partition somewhere (a directory), the previous contents of the directory are hidden.

It sounds like you mounted over the /home directory, which concealed the contents of the user's home directories.
You could either a) mount the partition to a subdirectory of your home directory, or b) use the options uid= and gid= in your fstab line, which together with the fmask and umask options can give a particular user exclusive access to the partition.

Have only dabbled in Slack. I think default desktop is KDE. Not sure if Slack has a GUI control center or killer drive partition utility like Mandrake, but:

Yes, make sure the partition is FAT32 so as to be "seen" by both OSs.

If you repartition your main (hda) drive with Wxp on it, be sure to defrag first and be careful and Backup!
If you use a second (clean) drive (hdb), be careful and backup!

Either way if slack does not have a utility that automatically detects a new drive and its partitions, you will want to add to your /etc/fstab something that looks similar to this using a simple text editor: ( You may also have to run this as root and change permissions of the fstab file).

/dev/hda#_/mnt/name_vfat_umask=0,user_0_0

where: # is the number that your FAT partition has been assigned by you or the partition utility
name is any name you choose for your FAT partition
_ are spaces

If you use a second HD use /dev/hdb#
Then, so that your system knows where to mount this new device, cd to /mnt directory and create a new sub directory with:

[localhost mnt]# mkdir_name

Now exit the /mnt directory with cd .. and you should be able to mount the device with:

[localhost /]# mount_/dev/hda#_/mnt/name

From here I think from within your home folder window, KDE gives you a way to right click -> create a new device ->hard disk dev -> select the FAT32 part you created. Then you will have an icon(link) to the partition. You may or may not have to play with some permissions to read and write.

good luck

A bit more refinement on this:

I would put Linux, Windows, and "data" on three separate physical drives--this minimizes the hassle if you have a "hard crash". Almost as good is two drives: One for the OSes, and one for data.

Depending on your configuration, you can use extra space on the OS drive(s) for backup. The best for regular backup is an external USB or Firewire drive---less ways for a computer failure to take out the backup drive with it.