I'm working on deploying Win 7 x64 to all of our clients, they are x64 ready machines but most are running 32 bit operating systems. I have a 32bit VM that I want to play with, but I'm having problems converting the VM to x64 virtual hardware so I can attempt my tests. I want to use a VM so I can snapshot and go back and try a few different things out. With VMware vSphere ESXi 4.1 is there a way to convert a VM from win XP 32bit -> Win 7 x64 guest hardware? I keep running into problems trying to change the scsi controller from bus logic to lsi.
ESXi 4.1 only really supports two virtualised hardware models, the PCI-based model 4 and the PCI-e based model 7 - both offer x64 bit support so I'm confused with your question, the issue is more to do with valid SCSI controller options between XP and W7 than x64 bit support. Please come back with more information, specifically on what exact version of XP you're using and what disk controller drivers it's using.
The hardware in and of itself is not 32 bit per se. Changing the guest OS setting to 64 bit will not change the guest OS to 64 bit. Any testing you want to do should occur on a 64 bit copy of windows. There is no way to "upgrade" to a 64 bit OS, you must to a reinstall.
Do you have any 64-bit Guest VMs running? If you haven't had them before, you may need to turn on a BIOS setting (Virtualization Technology) for ESXi to allow them.