Running Different OS On Two Hard Drives

I'm about built a new computer, but have a problem with storage. I currently have over 690gb of music and video over 3 internal and 1 external hard drives and intend on buying a 1tb internal drive to tranfer everything onto, to avoid burning it all to disc.
My current system runs windows xp pro (32bit) and my new system will change to windows xp pro (64bit). All the old hard drives will be formatted and removed from the old system for the fresh install, but the new hard drive will have all my stuff on with a partial OS, in windows xp (32bit) format. I would like to add, the new hard drive will not be the primary system drive in either new or old computers, just a storage device.


Will my new system recognise the new hard drive with the (32bit) OS and will all my stuff be safe or am I just going to loose it all?

My other option is to get an external hard drive of similiar capacity and the same question as above also applies.

Any suggestions greatly appreciated in advance.

 

I have 1.7 tb of storage on one machine (700gb internal 1tb external)and 1tb on the second all programs are on an external drive (except OS) and i just place a shortcut on my desktop to the applications i want to use and run them directly from the external.
In theory you could run an OS from external drive but USB would make it prohibitively slow.
My personal advice is load your OS to the primary internal drive and put all the rest on the external.