Ha! Free Open Source Software to the rescue. Used qtparted to resize the partition, and this forced Win98 to re-read the tables, and recognize the new size. This, btw, is the ugly old version 1, not SE, but both ask for Large Disk Support (same fdisk for both.)

Here's what I ended up doing:

1) Used windows fdisk to create a primary, bootable 6G FAT32 partition.
2) Used windows fdisk to create a secondary partition from the remainder of the 20G drive.
3) Used windows fdisk to create a logical 6G FAT32 partition at the beginning of the secondary partition.
4) Formated these c: and d: partitions with windows format.
5) Booted Knoppix (3.7, actually) with noswap cheat.
6) From root shell, restored c: from /mnt/cdrom1/file.partimg.gz, the partimage file with the win98 data saved from the prior 4G partition.
7) From said root shell ran qtparted, selected the new 6G hda1 c: drive, and selected "resize", then "commit".
Rebooted to Win98 boot floppy, sys c:
9) Rebooted to Windows and saw it hunt for drive info, and recognize both c: and d: as 6G.
10 Tested software, it all seems to work.

Next I booted back into Knoppix, used qtparted to create a nice 768Meg linux swap partition, and another ext3 from the remainder of the drive. Commit, reboot, and all is well!

Thanks for your help

snarkbait