Adding RAM doesn’t always speed up a computer

I was on computer service call in Fort Wayne last month for a client who had my business card and didn’t know where he got it. One of the issues they needed resolved was a Microsoft Windows Vista computer which was extremely slow. They had someone investigate last year and they never got it fixed. I started looking at the hard drive free space and it was acceptable. I defragged the hard drive, stripped all unnecessary programs from the computer and from startup.  It was still slow so I looked at the memory(RAM) and was surprised to find it only had 1 GB. This didn’t seem like enough. There are 4 memory slots on the motherboard with 2 of them occupied with 500MB sticks. I added two 2-GB sticks to make a total of 5GB and thought this would make it faster. To my surprise, it was still slow so I guessed a virus was present because it had inadequate security software. I scanned the hard drive with everything I had and didn’t find one infection. I gave up after much time spent and arrived at the conclusion Microsoft Vista was the cause of the slow computer. I will never try and speed up a Vista computer again.