Hey!
OK, a few points:
- You want to save a copy of the MBR before you partition the disk in the Ubuntu installer. You want to restore the MBR after you partition the disk. I would suggest doing so before installing GRUB. It just happens to be a good place to do it, when the grub install page is up. You don't have to perform these operations while the installer is doing stuff, and I wouldn't recommend it. Do them when the installer is waiting for user input.
- Don't forget that you have to tell GRUB to install to the main linux partition, not the swap. It isn't in the listed suggestions, you have to know which partition the linux main is. I've listed what it usually is in the instructions.
- Don't edit the boot.ini or any other Windows files. You don't need to.
- Virtual machines work great. In fact, I have a triple-boot macbook with several virtual machines on it for testing. The goal of triple-booting is to have any OS and have access to 4GB of memory. In a virtualized environment, you will always share the memory between the host OS and the VM.
OK, so if you've done any of this stuff and borked the process, I wouldn't bother trying to fix it. Either Ubuntu mucked the MBR so Windows won't boot, or you've otherwise lost the pristine MBR Windows requires, and you're screwed. Easiest way is to boot into OSX, fire up Disk Utility (it's in Applications/Utilities), crush all the partitions back into OSX and start over.
This is a very exact procedure, and everything has to be done perfectly. If you make a mistake, you're done.
