One of the biggest thing you hear people asking about their computers is "What can I do to make it faster". Many people are tempted to spend money on programs that promise to speed up their computers, programs that usually cause more harm than good and usually aren't worth even a part of the price you pay for them. As long as you run a good anti virus program as well as a good anti spyware program on your computer often, those types of programs aren't necessary.
In my own personal experience, one of the things that keeps a computer from running as fast as possible is the lack of the proper amount of memory required to run the computer and the programs and games that you use.
For instance, we have one computer left in the house that still runs Windows XP, and that computer only has 1GB of memory, yet it runs beautifully. But another of our computers that has Windows Vista on it has 1GB of memory and it's painfully slow! The different is that Vista requires at least 2GB of memory to run correctly. Unfortunately that computer came with smaller memory cards filling up the card slots, so in order to upgrade the memory we'll have to buy two 1GB cards, and the money just hasn't been there to do that.
So check your computers memory and make sure you have enough to run your OS as well as the programs and games you run regularly, you may find a boost in memory might be just the thing to give your computer a new least on life!