Reconfigure to boot from extended partition?

[NoOp]

Is it possible to reconfigure an extended partition so that it is bootable?

On the first ubuntu system that I set up last year I screwed up and
created the ubuntu partition as extended rather than ext3 etc. The
problem that I have now is that I must have the windows drive in the
system for it to boot. If possible I'd like to reconfigure the second
drive (linux) so that it can boot on it's own, but still retain all of
the data & configuration that exists on it. I'd also like to configure
so that I can still dual boot into the windows drive. The drives are
configured as:

$ sudo fdisk -lu
Password:

Disk /dev/hda: 19.2 GB, 19259154432 bytes
240 heads, 63 sectors/track, 2487 cylinders, total 37615536 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *          63    30088799    15044368+   7  HPFS/NTFS
/dev/hda2        30088800    37603439     3757320    f  W95 Ext'd (LBA)
/dev/hda5        30088863    37603439     3757288+  82  Linux swap / Solaris

Disk /dev/hdb: 41.1 GB, 41110142976 bytes
255 heads, 63 sectors/track, 4998 cylinders, total 80293248 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdb1              63    80292869    40146403+   5  Extended
/dev/hdb5             126      498014      248944+  83  Linux
/dev/hdb6          498078    80292869    39897396   83  Linux

Relevant parts of menus.lst:

title		Ubuntu, kernel 2.6.20-16-386
root		(hd1,4)
kernel		/vmlinuz-2.6.20-16-386 root=/dev/mapper/Ubuntu-root ro acpi=off
noacpi vga=0x0319 splash vga=788
initrd		/initrd.img-2.6.20-16-386
savedefault
....
# This entry automatically added by the Debian installer for a non-linux OS
# on /dev/hda1
title		Microsoft Windows 2000 Professional
root		(hd0,0)
savedefault
makeactive
chainloader	+1

Note: I've backed up the important data on the linux drive.

Can I simply reinstall grub and tell it to boot from hdb? ala:
http://users.bigpond.net.au/hermanzone/p15.htm#reinstallgrub
or will that just make matters worse?