Suspend To Ram will work in Win2K also if the sun and moon are in the proper alignment
STR is standby with no noise, ie it shuts off everything in your computer except leaves a trickle of +5 voltage to the memory to retain the data for all open programs. Once you flick your mouse to wake it up your puter is back where you left it, programs included, in about 10 seconds.
ACPI, in a nutshell, handles things like IRQ sharing and power management. Your Win2K box may already be in ACPI mode, to find out, go to device manager and click the + by computer to see what computer type it is. Hopefully it's already ACPI. At least for Win2K and depending on your motherboard, it may be necessary to clean install the o/s with a properly configured bios to get STR working properly. ALL hardware and ALL device drivers have to support STR for it to work properly.
Having said all that, in my experience XP probably does a little better job with power management than 2K.