What is the priority to upgrade the PC performance if you mostly work on video editing?

well you asked about the CPU or the ram from you description you have a good enough video card if it has 256mb on it.

your 1.8 P4 is good enough for video editing but if you have slow ram you are bottle necking your self there. you have 768mb but if its pc2200 or pc2700 you could upgrade it by getting some pc3200 ram even 512mb of pc3200 would be faster than what you have now. that should give you a noticiable differenve.

Ram is always useful in video editing and graphic manipulation applications. In the current (mid-2004) market, 1GB of RAM would be the maximum most graphic users would be able to use.

However, the new 64-bit systems will be the direction to head toward once 64-bit operating systems and subsequent application become more available and in general usage.