- It turned out that VMware Fusion was not the cause of the problem. Apple's Boot Camp was the cause of the problem:
I've got 3GB of RAM in my MP, yet WinXP only recognizes 2GB.
It seems the issue affects all versions of the Apple software (up to 1.4 as of this writing). It might be a problem in the legacy BIOS part of the Mac's EFI.
- Funnily enough, it also turned out that VMware Fusion was a solution to the problem. When booting your Boot Camp partition in VMware Fusion, Windows XP will see exactly the amount of RAM you have configured for that virtual machine, and you can crank that value up to 3.6 GB, at which point you will hit Windows XP's limit (the article claims the limit is 4 GB, but it actually is 3.6 GB).
So if you were planning to run a memory-intensive workload (like a database or a digital media authoring application) in Windows XP natively on a Mac, consider doing it in VMware Fusion instead.
For almost all devices, a VMware Fusion virtual machine is actually closer to a PC than an Intel-based Mac is. Currently there is one obvious exception to this rule: modern 3D GPUs. But if you attended VMworld 2007, you might have seen that we are actively working on removing that last hurdle...