Check if Windows uses the PAE extension inside the VM.
If you look at "System Properties / General" you should be able to read "Physical Address Extension" as last line in the Computer-section.
Without PAE Windows 2003 (32-bit) will only address 4 GB of memory.

You can force the usage of PAE by adding /PAE to C:\BOOT.INI like here:
[code]
[boot loader]
timeout=5
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /fastdetect /pae
[/code]

And - next time - please mark your post as a question (if it is a question like this one) so that you can reward points for helpful or correct answers.

Regards
Andreas