Well, my sister asked me today which is better, getting more RAM, or just getting a new computer. I'll do my best to explain.

Your CPU is directly responsible for the speed at which a computer program runs. If programs load slow, take a long time to do certain tasks, and your computer seems generally clunky, It COULD be that purchasing a new computer with a faster CPU would help speed things up.

Now, it gets complicated when you factor in costs of memory and disk access. Generally, when a program needs to access information, it first loads it from the disk and then stores it in memory. From there, it fetches it again from memory until the information is processed and then, usually, saves it back to the disk. Fetching information from the disk is very slow, and from memory is still quite slow, when compared to the speed that the processor is running and doing work at. This is true even for your older CPU. If a program is running slow, it is very important to determine if it is slow because the CPU is busy doing work, or if it is slow and the CPU is idle waiting for information to load.

The equation is further complicated by how computers manage memory. As long as the programs you have running don't take up all of your memory, your CPU can access the information it has loaded into memory without any delay. If, on the other hand, you load a lot of programs at once, or one program takes up a lot of memory, your computer takes some of the memory that isn't being used at the moment and saves it onto the disk. When you switch back to the program you weren't using for a while that had been swapped out, your computer has to load the stored memory from the disk back into memory before it can access it. This additional load requirement for memory access causes delays in program execution. In some cases, you might be attempting to load multiple programs that together, require more memory than you have. The computer would be forced to constantly swap memory back and forth from the disk in order to provide each program that which is request. This process is called swapping and can render a computer almost unusable.

In order to answer the question, it is important to figure out which scenario best fits your computers symptoms. If you are using Windows XP, you can right click on the task bar and choose task manager. Under the "Performance" tab, you'll be able to find information on how much memory is being used and how fast your processor is running. When you notice your computer going slow, take a look at how much CPU usage is being reported. Also, notice how much virtual memory is being used, and how much physical memory you have. If you you have a higher value under the "commit charge" setting than you have physical memory, you may find that purchasing more memory increases the speed of your computer. If however, you see a high CPU load, but notice you have plenty of memory left, it may be time to go ahead and upgrade your computer.

In short, a new computer system will probably make things seem faster regardless. It'll have a little faster processor, possibly more memory, and probably a better disk drive. If your problem is specifically related to memory however, you may find that spending $40 on another bit of memory makes all the difference you need.

Additional Notes:

  1. Here is some additional information on the task manager
  2. You have to make sure you CAN add more memory to your computer.
  3. CPUs can sometimes be upgraded too depending on what you currently have and what model of motherboard you have.