I *do* think there are other reasons.
Someone in this forum said, BIOS/EFI was just used to start the machine, then the OS would take over, so the boot ROM isn't important at all. This is not true anymore. During the last years firmware became more important again even on PCs, think of ACPI. And remember the time when ACPI was introduced. On a lot of systems you had to turn off ACPI in the BIOS setup at all to get Windows installed at all. Not because ACPI is bad, just because a lot of old implementations where extremly buggy (and still are). Or think back when they introduced USB (a technology mainly developed by Intel!). Most PC guys insisted on keeping a PS/2 keyboard, just because BIOSes had setups that where too dumb to be used with a USB keyboard.
Apple made EFI obviously work well, but a lot of PC and mainboard vendors do not have such high standards. They just put parts together without caring much about integration. Maybe MS is just glad that BIOS with ACPI (with all suspend-to-ram etc) now works quite well and they do not want hunderts of buggy EFI implementations with tons of support problems? And they know, PC makers will support BIOS for a long time, just because of XP and other "old" OSes, resulting in a EFI/BIOS "hybrid" of some sort, that could create even more trouble if it is not implemented well. Possibly this is a reason for them to start in the 64 bit and server segment, hoping for better quality than in the budget PC market.
And Apple ? Why EFI?
I think there are reasons that have NOTHING to do with Windows.
The first one is, a Mac with BIOS would not look and feel like a real Mac. When I switch on a typical PC, it makes a (legacy) beep , then it starts in a (legacy) text mode, then a Windows boot screen appears (in a legacy gfx mode) until windows finally boots. Imagine that on a 30'' cinema display

In contrast, when my iMac is set to 1440x900 it uses that mode from the very first second. You can't to that with BIOS, legacy VGA (or VESA) BIOS does not even support that mode ! There are other things (FireWire target mode and others). And even if they had BIOS and EFI, the user would have to choose what mode to use in some way, maybe even resulting in an ugly PC style BIOS setup menu?
That is not Mac experience anymore.
There is another technical reason. BIOS uses MBR (Master boot record) to boot the OS, a very old standard. It has a limit in disc size, more than 2048 GB is not possible. That sounds much, but 500 GB discs are widely available now, and I think a 2 TB disc is no more than 2 years away. (Note: I mean 2 TB per DISC, not per partition, so partitioning won't help). I'm sure the PC industry will find another ugly hack to get around this , as they did over and over again, but with EFI you (and all Mac users) do not have that problem: EFI introduces a new partition scheme (GPT) that does not have this limit at all.
OSX is installed on a disc partitioned with GPT, but no Windows version (other than the one for Itanium) can boot from such a disc. That means you could need 2 discs to dual boot. Not much fun on an iMac,Mini or MBP.
Christian
reyesmac said:
Either Apple made a deal with Microsoft so they would not make a Mac bootable version of windows or Microsoft does not want windows to run on Mac hardware... there is no third option.