And it’s somewhat of a moot point anyway – on 32 bit Windows, only 2 GB of RAM is available to user space programs, so everything above 2 GB is useless for gaming anyway. I’d suggest either using x64 or returning two of your 1 GB DIMMs for a pair of 512 MB DIMMs to save yourself some mony.
And it’s not a Windows thing either, it’s actually an IA-32 limitation. Linux has the issue as well.