The subject line pretty much says it all. But for details:

I've got a Vaio PCV RS221 w/512MB, 120GB HD, WinXP and an external 8GB USB HD on which I, *disastrously*, managed to load Lindows 4.5. However, after the "install" LILO went berserk and totally corrupted my MBR on the main drive. Long story short, I've since re-installed *everything* on the main drive, but now I don't know how to dual boot to the USB and Lindows. It's still there as I can see it if I boot LindowsLive. I spent too long doing a re-install of WinXP to try to re-install Lindows4.5. I just want to know how to use XOSL or BootPart and/or NTLDR to get the WinXP to dual boot with Lindows. Since I *THINK* that repairing the MBR on the main drive wiped out the 512 bytes that LILO wants, I don't know where to look or how to get what I need from the external HD. Could I just scan the Lindows 4.5 CD for the file and how do I tell WinXP to use it?

Any suggestions?

Well Derek, you might need to install a 3th party bootloader (like bootit or so). I am not sure that will solve your problem though. Your setup is a bit of the walked path imho. Btw, if it ever worked (and will work again) you really should make a boot floppy for cases like this. You would probably have solved the problem that way.
Simpliest now would be to use Partion Magic and reduce your 120Gb tot some .... (up to you) and install LindowsOS next to XP on the same drive. That should work fine with LiLo. What ever is on your USB hdd right now you can then recover and use the drive for other "tricks".
Saying that, I have prepared a few systems that way with XP running FAT32. Somehow NTFS always gave me one or another problem. Others say it shouldn't make difference but I can only talk about my own experiences. Talking about own experiences, I have also a external USB hdd (mainly as storage and backup) and it works fine with LindowsOS but in my case the drive will only be recognized if I start the system with the drive "on" and connected. If I plug it in while up and running I will never find that drive. Seems a little buggy to me. Well, at least you know!

The following was ever posted on the Lindows.com cummunity board. It seems a "mouth full" but maybe, depending on your skills, here's something you can use. It is about how to restore LiLo

""This how-to has been tested with LindowsOS 4.

You installed Microsoft Windows XP after installing LindowsOS then windows XP erased the MBR of your hard-disk. There is a way to rewrite the MBR so that LindowsOS will be back alive! What you will need is your LindowsOS installation CD.

1. Make shure that your computer can boot from the CDROM. If not then set that up into your computer's bios.

2. Put the LindowsOS installation cdrom into the drive, when you are promped with the choice, installation or Diagnostic, choose diagnostic.

3. Then you will see a bunch of nonsence stuff if you are not too used to Linux.

4. Then you will have a command prompt and your computer will be waiting for keyboard input.

5. For the simulation I will assume that you want to restore the MBR for Lindows on the primary drive of your system, and that LindowsOS is installed with the complete take over of your harddrive.

6. type, mount -t auto /dev/ide/host0/bus0/target0/lun0/part3 /mnt

This will give you access to your LindowsOS files under the /mnt directory.

7. type, chroot /mnt
This will change the / directory the the /mnt (Makes Linux think that the root directory is your LindowsOS partition.

8. type, cd /dev
Do I have to say what this does?

9. type, mknod hda b 3 0 Access to primary HD
10. mknod hda1 b 3 1 Access to the /boot parition

11. mknod hda3 b 3 3 Access to your main LOS part

12. mount -t auto /dev/hda1 /boot
This mount the /dev/hda1 partition under the /boot directory (The boot manager of LindowsOS use this)

13. lilo
This will read the configuration file /etc/lilo.conf and write Lilo back into the MBR.

14. rm /dev/hda && rm /dev/hda1 && rm /hda3
Removing those devices since LindowsOS dont use them

15. exit
...

16. umount /mnt
It may give you an error but it dont hurt to try.

17. Only if you got an error from the step 15 type sync, this will dump all non written data to your disks.

18. Well, remove the LindowsOS installation cd and reboot your machine.

19.You will now have LILO (Linux loader) back and you will be able to use your LindowsOS like a new kiddy.

Note:
Yes, I was so near to make this work, and when I saw that LindowsOS the /dev directory was empty I nearly thinked that this cannot be done. But I remembered that you can create those devices so I did it, and it works hehe. But you must also erase those devices after so that you dont have nonstandard LindowsOS stuff into that directory.""

I can't recall who wrote this. For some reason I just saved it to be studied later (which never happend so far, LOL!). Hope it can be of use.