I have a 64 bit box and installed suse 10.0 32 bit. I then wanted to use the remaining hard disk space to install suse 10.0 64 bit. During the install, suse said it would 'format partition /dev/hda5 (1.9gb) for swap' and 'create root partition /dev/hda7 (53.3 gb) with reiserfs'. My concern is that suse 10.0 32 bit is already using hda5 as a swap partition. If I let the installation go ahead, will this affect suse 10.0 32bit in any way? Here is a list of my hard disk partitions:
hda1 is windows
hda2 is fedora boot
hda3 is fedora root
hda4 is extended
hda5 is suse 10.0 swap file (32 bit)
hda6 is suse 10.0 root (32 bit)

I share one swap partition for all my Linux distributions.

Then the installer was correct and I can accept its default settings. The installer was going to use 53 gig for suse 10.0 64 bit root (hda7) from the remaining extended partition (hda4) of about 70 gig. Is it safe to modify the partition settings and use all available space on the drive or should some space remain as extended?

You can only have 4 regular partitions. One of these regular partitions is /dev/hda4.

If you want to save space, the location of a users home directory is determined in /etc/passwd. You can use the same home directory for the home partition. You might want to add a suffix to the name to prevent clashes between different versions of KDE for example. Also, if the UIDs are different, you won't be able to access the /home/user of FC from SuSE.

In some environments, the home directories are located on network drives. In a heterogeneous environment, you may have many of the system partitions mounted on shared read-only (static) shares.

Then the root partitions are not counted as a regular partition? If that is true, then I now have 3 regular partions?
1. Windows
2. Fedora
3. Suse (32 bit)
I can add one additional partition? I am not sure what you mean by a 'clash' caused by two different versions of kde.

I just installed suse 10.0 64 bit and everything is fine with my multi-boot system. The install was very smooth and it runs stable. So yes, 32 bit and 64 bit can share the same swap partition.

All a swap really is is empty space to write .tmp to when your regular ram overflows. U can have as many linux OS's sharing a single swap as u want ( given u configure corectly) i have suse 10.0 , 10.1 and knoppix V5 share one swap partition.