Have a look at this information from GParted:
/dev/sda4 starts at sector 281106430 and ends at sector 312580095.
/dev/sda5 starts at sector 281106432 and ends at sector 310482943.
/dev/sda6 starts at sector 310484992 and ends at sector 312580095.
The way I set up all these operating systems was I set up the first 2GB FAT16 partition for DOS, installed that, then installed PLoP with floppy installer and created the hda1 and hda1-hidden partition definitions.
I created the DOS profile HDA: *80h hda1, clear, clear, clear and a Windows 98 profile HDA: hda1-hidden, *80h don't touch, clear, clear.
Then I used the Windows 98 installer to create a new 15GB FAT32 partition, installed it, then re-installed PLoP bootloader from the diskette again. Then I created the hda2 and hda2-hidden partition definitions.
I updated the Windows 98 profile to HDA: *80h hda2, hda1, clear, clear and created a Windows XP profile HDA: hda1-hidden, hda2-hidden, *80h don't touch, clear.
Then I used the Windows XP installer to create the third 117GB NTFS partition. I've found that the Windows XP installation would not work unless I used the partition tool included on the installation CD.
Then again I re-installed PLoP bootloader from the diskette and again created the hda3 partition definition.
I updated the Windows XP profile to HDA: *80h hda3, hda1, hda2, clear and created a Lubuntu profile HDA: hda1, hda2, hda3, *80h don't touch.
For Lubuntu I used the installation CD to create the /dev/sda5 (14GB ext4, mount "/") and /dev/sda6 (linux-swap) partitions. After the installation it seemed there was nothing at boot, just a flashing cursor. I had to again re-install PLoP bootloader from diskette and lastly created the hda4 partition definition.
Finally, I updated the Lubuntu profile to HDA: hda1, hda2, hda3, *80h hda4 L1.
I've tried creating the Lubuntu logical partitions using both GParted and the tool in the installer and neither way seems to make a bootable system !
Oh: and one time I used the GParted tool to set the "boot" flag on /dev/sda5, seemingly to no effect.