Updating the ram

I bought a dell demension 4600 about a year ago I have four slots for ram in my computer two white ones with 2 x 256 in total 512mb ram there is also two black ones not used this is the system info i got:



SYSTEM MEMORY



DIMM: 256 MB SDRAM (white)

DIMM: 256 MB SDRAM (white)

DIMM: (black)

DIMM: (black)im not sure that looks right



so what i want to do is put 2x 256mb ram card in the black space's but im not sure if it will work i put a link in so you could see what i mean sorry its so god damn big



http://www.geocities.com/s_m_w_d/100_6417.jpg

I had a p4 like that, I believe what the rule was.... You must match the ram in the first 2 slots withthe ones in the back 2. So if you wanna add more ram just buy 2 sticks of identical ram example 2x128 or 2x256 or 2x512. Also i belive you mus put the largest ram sticks in the slots which are occupied right now. So if you got 2 mor 512 you would pull out the other ones and pyut in the new 512's. It was a while ago, but i think this is right.. Any confirmation?

so it is possiable just have 4x 256MB ram card!

yes

Its always a good idea to make sure all the ram is the same size. Not mandatory on some systems, but a good idea.