Due to the advancements in PC technology most software companies have had to keep up. This means that the latest essential Anti-virus, media player software or even just surfing the web is orientated towards faster more powerful computers.
Luckily the price of hardware has dropped considerably in the last couple of years making it possible to upgrade your current PC to latest standards on a tight budget.
In most cases it is even possible to use some of your existing hardware e.g. monitor, mouse/keyboard and of course internal hardware such as CD-Rom drives, hard disks and modems etc.