Thanks for trying. I looked at the link and I still don't know the answers to the question posed - What programs need NET Framework. If you do an internet search, there are many instances of average computer users trying to figure out what this is and whether it's needed. There is a great need.
Funny that the title of this website is "Tom's Hardware."
If you're not getting any programs prompting you to install .NET framework, then chances are you don't need it. ATi's Catalyst Control Center does require .NET framework to run... but if you don't have an ATi card, then you need not worry about it.
Simply put... if your computer is running properly and all your programs are running without errors, then you likely don't require .NET framework. I usually install it anyway, but there's no saying that you need it. I read the wiki link too... and there is nothing about any programs requiring it. Again though, any programs that require it will either prompt you telling you that you need to install it before the program will run or they will install it for you.
Vista does have .NET Framework 3.0 out of the box... thanks for alerting me to that, ijack. Although some programs designed for 2.0 may not work unless you install it first. So my original point stands... if you aren't being prompted that you need it by the software you are using, then you don't need to install anything.