memory usage comparison on WXP

[macro]

I will ask the question in a general way although an answer may depend on more specifics. Should I expect that an installation of Windows XP Pro in a VirtualBox VM configured as closely identically as possible to a Windows XP Pro on a physical machine ought to utilize the same amount of RAM in its normal state? In general, then, how should the memory usages of these two systems compare, under an assumption that everything else is equal? Is there a minimum amount of memory that would need to be made available before their systems become comparable in other respects? Does that make sense?

[mpack]

The guest OS will require and use the same amount of memory whether the hardware it runs on is physical or virtual, after all it doesn't know there's a difference.

However a VM requires resources for the simulation - it needs RAM for buffers, in fact it needs a whole host OS to be installed, so on the whole it will obviously require more resources to run XP as a VM than it would to run XP natively.