How to restrict Windows memory usage

In order to restrict the memory that Windows can use, starting from Vista you can use the command bcdedit (run from a Command Prompt with Administrator privileges):

* To remove 1GB (1024 MB) of physical memory from what can be used by Windows:

bcdedit /set removememory 1024

* To view the curent settings:

bcdedit /enum

* To remove the settings:

bcdedit /deletevalue removememory

ALTERNATIVELY, BUT NOT RECOMMENDED:
 
* To set the physical address limit at 1GB:
bcdedit /set truncatememory 1073741824
OR (in hexadecimal)

bcdedit /set truncatememory 0x40000000

* To remove the settings:

bcdedit /deletevalue truncatememory