I was asked to fix a Dell 8200 Dimension, 1.8 ghz, 2 128 mb memory with two other sticks I have no clue what they are, and operating with Windows XP. They want me to increase the memory but I am not able to find the ram, looking on newegg. The specs say it can hold 2gig in 4 slots. Do I have to use all four, 4 512 sticks, or can I use 2 1 gig sticks?