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.