Windows 2003 64 Bit memory utilization?

[Adi]

Hi,
I heard that Windows 2003 on 32 Bit Operating System only supports 2Gb
of memory per "Memcached instance"? I just want to know how much
memroy can be utilize in windows 2003 64Bit? what is the limit of
memory sizes with respect windows 2003 32 OR 64 Bit operating system?

Thanks