Open Boot.ini with notepad after changing the "Read only" attribute.

In the lines found underneath [operating systems] and add "/3GB" to the end.  An example is below:

multi(0)disk(0)rdisk(0)partition(1)\WINNT="Windows NT Workstation Version 4.00" /3GB 

This tweak only works for the "Enterprise Edition" of NT Server.

For More Info Visit: http://support.microsoft.com/support/kb/articles/Q171/7/93.asp