I just got two desktop computers. Two emachines. I only plan to use one, so my question is, can I take out RAM from one computer and put in the other to boost performance?
You should be able to if both of the computers use the same kind of RAM and if the motherboards has extra slots for more RAM. You also have to check how much RAM your motherboard can support. Putting more RAM then your motherboard can support would be a waste.
Well first make sure the one you want to use has a 64bit os, adding more ram to a 32bit os won't do a whole lot. This is a good scanner to use to show how much ram you have, how many slots you have available, and the type of memory it is. http://www.crucial.com/systemscanner/ But yeah, more adding ram is a fairly simple task.
Well a 32bit os can only see about 4gigs of ram maximum, so if you were trying to add more then that I would suggest switching to a 64bit os first.