Processors are ranked by the speed with which they can receive, understand and act on information, measured in megahertz. In real life, the processor's speed is inhibited by the limitations of other components, with the result that speed differences between modern computers are barely noticeable to beginners. A fast processor is a great help for tasks like graphics, but makes scant difference to word-processing or the Internet. The other part of the computer's 'brain', which determines what quantities of information the machine can process at once. Modern graphics programs choke on anything less.
More RAM is worth the extra money.
Just as no house can ever have enough cupboards, no computer can ever have enough hard drive space. The problem's made worse because modern software gets more bloated and space-consuming each year. More is good, much more is better. Standard graphics cards use two megabytes of a mysterious substance called video memory. Game fanatics and graphic designers use cards with 16 or 32 megabytes of video memory.