I currently have Win 2K, Suse 9.1, and RH 9 on my system, however I want to put all my linux distros into one HDD. I currently have 2 HDDs - 120 GB for Win 2K and my data files in mulitple partitions, then I have a 60 GB HDD that has one partition as a backup location for files and 3 other partitions for suse, rh, and swap.

this is what I was thinking of doing:

hda - keep as is with ntfs system

hdb - split as follows or similar:
hdb1 - ntfs (backup for files)
hdb2 - /root (suse) 100 mb ----------------------
hdb3 - /root (rh) 100 mb |
hdb4 - /root (ubuntu) 100 mb these could potentially change
hdb5 - /root (slackware) 100 mb |
hdb6 - /root (any other distro) 100 md --------
hdb7 - /home about 6-10 gb
hdb8 - /var about 5 gb
hdb9 - /tmp about 1 gb
hdb10 - /usr about 6-10 gb
hdb11 - swap

would something like this work or would I have to have each distro installed on it's own 2-5 GB partition while sharing access to /home, /var, /tmp, /usr, and swap?

Hopefully this makes sense.
Also I am considering having a boot disk for each or all of the distro's together.

You can share swap between the linux OSes without issue. And you "may" could share /home but you'd have to setup all the GIDs & UIDs the same under each OS and take care of a host of other issues such as X Desktop settings and etc, so I wouldn't recommend it. And /tmp may also work. As far as /usr, /var and everything else goes, that wouldn't work with different OS, or even different versions of the same OS because all the binairies for one would link against a different set of libraries than the other normally.