Ghloria, how much ram you can usefully add depends on your operating system and motherboard. Can you tell us what they are? I find that between 128M and 256M is ideal for Windows 98se. Up to 128M you will find that your computer responds much more quickly, over 128M the improvement will not be as dramatic. If you are going to edit mpeg files you will certainly need more memory than you have now. To handle these large files without extra memory, your computer will be constantly having access the hard drive to store and retrieve data. With extra ram this will not have to happen as often.