I'm worn down by researching many of these steps (I began netsinstall over 48 hours ago). (also running out of energy to correct my congenital typos :-) )
I've paraphrased installation quotes in the following.

abridged history: "small form factor" with flaky laptop type cdrom (wouldn't boot from burned install cd). 700mhz, 512mb, huge HDD. fresh winxp in 1st partition (scsi2 (0,0,0) sdb ntfs primary partition #1). (sda is external USB HDD)

Google found method to startup jaunty's initrd.gz,etc via menu.lst on HDD. Partitioned as:
scsi2 sdb
#1 primary 61.9 gb b ntfs [winxp install]
#2 primary 61.9 gb f ext3 [ubuntu 9.04 install, imminent]
#5 logical 1.0 gb f swap [winxp install]
#6 logical 35.3 gb [chose "do not use" space that remains]

Install "predefined collections". I chose Ubuntu desktop, Samba, DNS, Basic Ubuntu servers, and "manual [blah blah something that chooses packages?]".

Install finished aptitude updater (terrible UI, btw.)

Current question:
Grub has downloaded. installer pane says it has found winxp.. "should be safe to install boot loadre to MBR of 1st HDD."

Seems OK, except that I already know I'll either repair or completely reinstall xp (xp wouldn't connect to lan & 9.04 netinstall proves hardware not the cause)

When I tell grub install to not install to MBR, the next screen gives syntax examples of other grub locations (including to a floppy, which I could easily protect from xp reinstall). Will these locations be safe from molestation when I reinstall winxp? Or can I skip grub install, and later install another boat loader?)

So, I googled "repair grub [etc]"
http://onlyubuntu.blogspot.com/2008/...r-windows.html
Looks easy enough except that it requires cdrom to boot livecd.

http://help.ubuntu.com/community/Rec...Grub%20Disk%22
(text preceding this section is huge and looks as if requires booting into ubuntu)
Summarizing this section:
1st option: I choose either: grub in MBR or "windows chainloads grub"

2nd option "windows chainloads grub" looks more flexible, but does it have any drawbacks compared to grub in MBR?

I thought I saw a 3rd option(?) further down this webpage. It mentions other boot loaders (but doesn't mention GAG or XOSL).

Any tips? questions?

Thanks...

I always prefer grub in the MBR - it's easy enough to fix if/when XP trashes it.
However... I wouldn't trust the installer not to actually put it on the external disk MBR. Again, easy enough to fix, but something else that may confuse you.

So, that leaves install to the root partition. You can't directly chainload from the XP loader like you can from Linux loaders - you have to dd the boot sector record and copy it to Xp, then add it to boot.ini.

You'll have to decide which is easier and/or more understandable for you.

if that's as reliable as other setups, and the easiest to fix, then that's best.

I pulled the USB cable, but the installer panes continue to believe the USB HDD is still connected. So it could be interesting watching how installer responds if I choose the default (grub to MBR). :-)

Yeah, too much unfamiliar there after googling (dd... XP loader is boot.ini plus uneditable ntldr etc?)
I guess I'll let it try to install grub to mbr. if it complains, then maybe it will let me specify the 2nd partition (Ubuntu).
Next. If it doesn't offer both OS at reboot. I'll try to reinstall Ubuntu from very beginning (intrd.gz, etc)
At worst, I redo completely (fresh XP partition &install, then..) No docs to worry about losing.

Thx..