Sorry man, I read it wrong. I thought you were askin "where" it was allocated to... My bad.
NT allocates 4GB of address space for each application with 2GBs reserved for the operating system and 2GBs reserved for the application. Windows 2000 and NT4 SP3 or later allow you to change the 2/2 split to 1GB for the operating system and 3 GBs for the application. This would obviously benefit SQL server or Oracle databases. If you have a large amount of memory and an application that can benefit from changing the 2/2 default, you add the parm /3GB to boot options lines in BOOT.INI.