I have a Dell Dimension 8250 desktop computer. I want to upgrade the ram memory cards. It now has 4 128k PC800(non-ECC)cards. It can be upgraded to 2gb running 40ns or faster. Questions are, what will give me the best increase in performance without costing an arm and a leg? As you know I have to upgrade in pairs. Replace the front 2 or back 2 or all 4? I want to get another 1-2yrs out of the computer. When re-booting I sometimes get a "system memory is low" prompt and it is not as fast as when new. Any help appreciated.