[WindowsCentral.com]

If you have an old PC with only a mechanical hard drive inside and it's getting too slow, an SSD is a cheap and easy way to get a big speed increase.
Over time your PC will slow down, that's just the sad nature things. If you're using an older PC that doesn't have any form of SSD inside it, however, there's one very simple thing to do that will reap you some significant performance increases.
A mechanical HDD will never offer data transfer speeds that an SSD will. Even a low-cost SSD will vastly outperform even the leading HDDs. A HDD-only system will be slow to boot up, slow to load apps, slow to read and write files.
For not a lot of money and a spare couple of hours you can breathe new life into your PC. Here's everything you need to know.

Full story from the WindowsCentral blog...