If that is really all you do, and more importantly all you ever intend to do, then leave well alone as you will not gain any great benefit from the upgrade. Personally I found Vista O.K. as an OS and I have only moved on to Win 7 because it came pre-installed when I bought a new computer. Save your money and have a good night out instead, you will feel more benefit from that!!!
How to watch Wimbledon 2015 live online: follow the tennis from your laptop or PC