Thank you for your advice last time. I'll try to ask with more info. this time. I have a 2003 presario s4100nx. Can the cpu be upgraded without changing other components? It has a celeron 2.5ghz cpu ,frontside busspeed 400mhz, processor architecture mPGA478, chipset 845GL. This computer will be only used for basic needs so I want the best speed for the lowest cost.Thank you.