How much RAM does Windows XP support?

[ua549]

Only 32 bit Windows has the 4GB limit divided between Application and OS 2/2 or 3/1.
64 bit Windows can handle 4GB per process.

Here is a rundown on physical memory support.
Windows XP Home & Pro -- 4GB
Windows XP Pro x64 Editions -- 16GB
Windows Server 2003 Web & SBS -- 2GB
Windows Server 2003 Standard -- 4GB
Windows Server 2003 Enterprise -- 8GB
Windows Server 2003 Enterprise on X86 -- 64GB
Windows Server 2003 Enterprise on x64 -- 128GB
Windows Server 2003 Enterprise on Itanium -- 1024GB

In addition there are many proprietary modifications to the Enterprise editions that extend the memory capabilities for large proprietary multiprocessor systems such as those offered by Unisys.

[I4one]

rock;
i realize how awkwardly my question actually reads - but the answer then, is YES ! -- as in there's no 2/3GB per process limits for apps written for x64... (i.e. apps written in 64bit code, not merely 'supported' through backwards compatability).
thanks ua - there's another list somewhat like yours in the ms link i posted - and this is interesting;

>> Windows Server 2003 Web & SBS -- 2GB
>> Windows Server 2003 Standard -- 4GB

so i assume 2k3 SBS is cheaper in cost of OS vs 2k3 Standard ?
why only 2GB total ? it's a Small Business Server ?