enter /3GB in C:\Boot.ini of your m/c like this
multi(0)disk(0)rdisk(0)partition(1)\WINNTSVR="Microsoft Windows 2000 Advanced Server" /3GB /fastdetect
Windows 2000 Advanced Server allows to increase the memory available to the process from 2GB to 3GB. This is referred to as 4GT, or 4-gigabyte tuning, because it changes the distribution of memory within the 4GB process address space, giving only 1GB to the OS, and leaving the rest for the process. The feat can be accomplished by adding the switch, /3GB, to the boot.ini file.