We recently upgraded to Windows 7 64 bit (workstations) and Windows 2008 64 bit (servers). To prevent loosing configuration information, and complex settings, we created a multi-boot system when upgrade was not option (i.e., when original installation was 32 bit, you cannot upgrade to 64 bit).
Simply mounting the volumes is not what I'm after. I've got some backups as ISO files, these are inherently read-only, and need to be converted / unpacked to be able to run them as virtual machine. Others are on bootable partitions.
Given a physical and bootable Windows Vista, XP, 2003 partition, what virtual machine software can I use to access it if that partition is on the same physical machine I currently run, preferably without conversion or copying.
With vmware you can use physical disks instead of vmdk files if you need to boot them, etc. (If you play on doing this then the easiest way is to boot them on the physical machine and install the vmware drivers)
Alternatively you can use something like norton ghost to copy a physical partition or iso into a vmdk file.
Also if you only need readonly access you can mount iso files on the virtual cd device.
Most virtualization software can easily run from a physical drive. However, most Windows solutions require access to the whole drive. If you have a single drive with two partitions (old and new) you'll have to copy the contents to a VHD or VMDK. If the OS is XP/2003 or older, you'll have to mess with the HAL and driver to get it to boot in the VM.
This is not a good situation to be in; the upgrade was done without a plan for continuing operations. This is where an ounce of prevention was worth a pound of remedy.
trying to use passthru disks in this case won't work for either esxi or hyper-v, they need exclusive access to the underlying drives. And in this case your booting off that drive thus you can't have exclusive access. boot into the old os and use disk2vhd to p2v these things.
I have done this in the past (for really weird reasons). I downloaded a trial of System Centre Virtual Machine Manager (http://www.microsoft.com/systemcenter/en/us/virtual-machine-manager.aspx). You can then convert a physical machine into a virtual one using the software. This then allows you to boot the machine of Microsoft Virtual PC (which is free) or Hyper-V server. Then just scrap the 32bit partition and extend the 64bit one to free up your space!
I used it to virtualize a server, move it onto a different machine so i could upgrade it back onto the original hardware as an inplace upgrade wasn't possible. Messy but it worked!
I'm slightly confused by your question to be honest, it could do with a rewrite - but if I understand correctly then my answer would be that VMWare ESX (you don't mention which product you're talking about) allows you to mount ISO files as an emulated CD/DVD - this might be what you want.
You could use VMware Converter and convert the original machine. Then, just add the resulting VMDK files to your new 64-bit VMs.
To simply connect, not boot, off of an ISO, you can mount the ISO on the host system (E.g., using a loopback mount for Linux) and then map it to the VM and mount it there as well. That will give you easy access to all the files.
Most VM's will allow you to boot off of an ISO CD image, in the same manner as real hardware boots off a real CD.
This is not quite the same as mapping an ISO image to a virtual disk, as it requires a "Live CD" type cd-based O/S, or at least an install type CD that will expect an installation target (blank VM disk). If your ISO is just a boot partition dump and not a crafted CD boot environment, a lot of things will not line up and the boot will probably fail.
In other words, if you can live without an actual P2V boot experience, you can still mount and get to the files on the ISO's.