If your PC is getting a bit long in the tooth, the temptation to replace it with a newer model is always there. The very latest in top-spec laptops, Notebooks, PCs and computers are constantly advertised and the pressure to buy the latest model is intense. The price of new technology is far lower proportionally than when computers first became a common household addition, but do you actually need to replace your entire system or can you save yourself time and money by upgrading what you already have?
The question you have to ask yourself is: does my current computer do everything I want it to do? If the answer to that is yes, then your current system will probably be sufficient for some time to come.