The decision to upgrade is an idividual one.
I can give you my experience.
Basically Windows 7 is Vista under the hood, but with a lot more eye candy and improvements.
Vista SP1 is not going to be supported much longer and SP2 will stop support a few years later.
Seven is the now.
Support and help is available.
Bottom line, I am happy that I went from Vista to Seven
You can buy an upgrade version for about $125.00.
If you do, you can come to our Seven Forums and I will show you how to install it just like it was the much more expensive full version.