why would you want to ?
they both do the same thing right ???
anyway, the only way i can think of, (which is messy)
is to re-run the linux install, (by booting install disk)
in the partioning part of the install, make an extra partitino out of the free space in hda2 (the main linux partiton) make it 700 megs big.
set the current /boot partiton to be formated,
and the /swap to be formated, but NOT hda2, leave that alone.
set the boot loader to grub, set the minimal install packages..
when its finished, boot. (it will boot the new install, minimal)
use it to edit the /boot/grub/grub.conf file with a command line text editor.
so that you set the main partiton (with all the data and prorams back to hda2, (probably from hda3)
you should then boot your old install, the one you have now from grub.
you can then use yor fave partion tool to remove the partiton you created
and add its space back to hda2..
you get it ????
anyway, that should work, ive never done it, but in theory, it should work,
you might want to get a second opinion though.