|Calling eMachines support isn't helping matters, it only helped to muddy the water. You have to understand that these people generally are not "techs". I can't find a ET1600-05 at the eMachines site nor does it come up when doing a google search, so I can only assume that's the wrong model number. My guess is it's an ET1160-05. But there are two things I know for sure:|
1. the A64 LE-1600 is a socket AM2 CPU.
2. socket AM2 motherboards supports 240-pin DDR2, not 184-pin DDR1.
So if eMachines support said that you need PC2700 RAM, they are totally incorrect.
You said you have 1GB RAM installed. That's really not very much these days, especially for Vista. And assuming you don't have an actual video card, a portion of that 1GB is being used by the onboard video. That means that Vista is actually operating with less than 1GB...my guess would be either 768MB or 896MB, depending on the graphics setting.
Check the model number of your eMachines again & post back. Could it be this one?