This has been an interesting yet easy thing to do. It takes me back to when I used to hunt down the versions of Java that were installed on my computer. Cannot tell you the love I have for Java and the many revisions of framework that Sun seems to put out every 5 days (exaggeration).
So what and how do I find out if my current version of Windows has the right .NET framework installed? Well like checking your Java version you usually would go to control panel and “add/remove programs” or if Vista/7 you would go to “Programs and Features”. Inside this list of programs that are installed on your computer you scroll down to the microsoft Service Pack X.XXX and see all the patches and what not. You could also go to your C:\Windows directory and open Microsoft.NET folder open the folder called Framework. Inside you will find folders like V1.0.3705 to V3.5. These are the versions of .NET framework installed on your computer.
2. Another interesting way to do it is:
Navigate to this Windows Registry path:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP
The major version number of each .Net framework releases installed can be found at this Registry path. Click the major version number key and there is a string value called “version” on the right-pane that reports the full version number of that .Net framework.
3. Or try this: Navigate to the Registry path that keeps the IE User Agent String:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform
There is also some pretty good software that will tell you the version of .NET you are running. Called oddly enough Version Checker.
So now you have no excuse not to know which version is installed on your machine.