Does windows server 2008 R1 x64 with sql 2008 R2 support the /3gb memory switch?

On Windows Server 2003 with SQL 2005 I know you could allocate only 1gb of memory for the OS and 3gb for applications.  Is this a viable option in Windows Server 2008 R1 x64 running SQL 2008 R2?  I have 4gb of RAM on the box and it seems to allocate memory, but only actively use about 45%.  The server will have reports run against it during the day and be performing an ETL process at night.  I did find the following link which explains what I already know but doesn't really say whether it is an option or a good idea for this scenario: http://msdn.microsoft.com/en-us/library/ms178067.aspx

I know there are things they can do such as optimize the ETL process to make sure they are selecting only columns that they need and not entire tables.  We can give it more memory, but we want to make sure the configuration is optimized first before throwing more resources at it.  Please help!