Which is better to install on Win 7, .NET 4.0 or .NET 4.5?

Until this date, Windows update only installs .NET Framework 4.0

I do have .NET Framework 4.5 installer which I always used to install

any reason why the Win 7 update is not installing the 4.5 version? Should I stick to 4.0 on the next Windows update or just install the latest as soon as I install Windows?

Windows 8 has 4.5 by default

 

From what I read 4.5 replaces 4.0 on win 7. So if everyting is working fine on win 7, I would keep .NET 4.0. I would only upgrade if a new game (for instance) required it. Good Question, I noticed I have 5 versions installed using "4. Manual Check" here: 4 Ways to Check What Version of Microsoft .NET Framework is Installed on your Computer ... Apparently this is not a problem.

 

I see, ill just stick to 4.5 then

 

IIRC, how it works is that .NET 4.5 is backwards compatible with 4.0. But those are not backwards-compatible with 3.5. 3.5 is backwards compatible with 3 and 2. But not 1.1. 1.1 is backwards compatible with 1. So to be able to run all .NET programs, you'd need 4.5, 3.5, and 1.1. Though there aren't very many programs that require .NET 1.1 and are still in common use.

Windows 8 may well have 3.5 and 1.1 installed by default in addition to 4.5, but if you're trying to run a .NET program and it complains it can't find something, try 3.5 and then 1.1 in that order. .NET 3.5 programs are still pretty common.