Thanks for some input on this!
Actually, the Linux swap partition is written as 500MB vs 5000MB (tenfold less than what you may have thought you measured), so that the sum total of logical partitions in this case come out to 13500MB (a.k.a. 13.5 GB).
The reasoning behind a 500MB swapfile is that this is approximately twice the amount of installed physical RAM of 256 MB.
The 14000MB extended + 5040MB primary-partitions would yield a 195040MB sum total (a.k.a. ~19.5 GB) for
all partitions within this 20 G hdd.
In this 5040 MB primary partitioning scheme, the reasoning for this space division is supposed to be based upon that difficult-to-reconcile use of the Master Boot Record (MBR). The FAT16 DOS and Windows9x OS's are perfectly flexible about installing to a second primary partition within a hdd's MBR. The NTFS WindowsNT and Windows2K OS's have been known to be much less flexible upon my own multiboot systems and have required me to use the FAT16 FDISK when these NTFS OS's muck up (reformatting to get rid of NTLDR too!) Suggestions for Linux multiboot systems almost always include making a small 1st partition (15-20MB) in the MBR itself to handle a /<root> partition past cylinder 1024. This small /boot partition in the MBR contains LILO or GRUB and is supposed to manage fat16 OS's, Linux, and ideally FreeBSD. Chapter 12 of the
FreeBSD handbook is still unclear on this handling of the MBR for multi-boot systems that include FreeBSD.
It seems that
every OS boot manager wants to handle for itself the MBR -- to the possible detriment of other installed OS's (examples of this grabbiness are NTLDR, LILO, boot0, maybe GRUB??)
See also the Figure 2-14. Sysinstall Boot Manager Menu in
the handbook's Choosing What to Install section.
If LILO turns out to actually be the best option to run either NTLDR, the compressed Linux kernel or the separate load stages of FreeBSD, then would the correct install order actually be more
DOS/Win9x
WinNT/Win2K/WinXP (if absolutely essential)
Linux w/ LILO)
FreeBSD

???????
Also, would it really be better (or even possible) to partition and install FreeBSD subslices using Sysinstall w/in the third 4000MB primary partition of the hdd as shown above, or else create a FreeBSD slice and subslice this at the
very end of the hdd ???
FYI, would much rather prefer starting out with the more lightweight XFce as per handbook section 5.7.4, than with GNOME or KDE.