Is dual boot possible with Vista Ultimate 32 and 64 bit OS?

I have an HP Pavilion m8000n with a 500GB hard drive and 2GB of memory. It initially came pre loaded with XP when I bought it (no recovery discs) and when I upgraded to Vista Ultimate I didn't realize that I may have chosen (or it was my only option) to upgrade to a 32 bit version when my computer can run the 64 bit version. I obtained a 32/64 bit version from Microsoft and realize that I have to do a fresh install of the 64 bit version (and upgrade my memory) wiping out the existing 32 bit version that has all the pre-loaded software when I originally bought the computer.

I plan on installing a 2TB internal hard drive (splitting to 2 1TB partitions) and upgrading the memory to 8GB. Before doing so, I'm going to image the existing 32 bit version and reinstall once the HD and memory upgrades are completed. If something should go wrong, I'll have the old 500GB HD and an image copy as well.

Is it possible to run a dual boot system using both Vista Ultimate 32 AND 64 bit versions?, and if so how would I go about doing this?

I have an another older computer with Windows 98/2000/XP pro (triple boot), but is been a while since I did this and would like to upgrade my m8000n to the proposed configuration mentioned above.

I'd greatly appreciate any and all the help/advice that I can get through this forum.

Thank you, I look forward to your response.

Hi,

This might help with the memory stuff for 32 & 64 bit: -

Memory Limits for Windows Releases (Windows)

As for the dual boot, follow this advice from: -

http://support.microsoft.com/kb/919529

Creating a multi-boot configuration that includes Windows Vista

To create a working multi-boot configuration, install the oldest version of the Windows operating system first. Then, install each newer version in order. Every new Windows version preserves backward compatibility for starting earlier Windows versions.

To create a multi-boot configuration that includes Windows Vista, you must have at least one partition for each earlier Windows version that you install. Follow these general guidelines:

• Create at least two partitions. Use one partition for the Windows Vista installation.
  
  Note If the partition for Windows Vista is already formatted, make sure that it is formatted by using the NTFS file system. However, we recommend that you use one of the following methods:
  • Create the second unformatted partition.
  • Do not create the second partition and leave the space as free space. Instead, create the second partition during the Windows Vista installation.

Click to expand...

Additional info on system requirements, System requirements for Windows Vista

As for the dual boot, Lottiemansion's post above explains how and shows that it is possible.