Why is the usable memory on my Macbook pro shown as 2.74 Gb when there is 4GB installed with 32bit Windows 7?

I have a Macbook Pro with 4GB of installed RAM. I have installed Windows 7 on it which shows the usable memory as 2.74GB. Why is this? Don't tell me the 32 bit story; I program for a living. The maximum addressible memory on a 32 bit system is 4 GB not 3 GB.

Need proof? MSDN: Memory Limits for Windows Releases