.NET applications opensource?

[P_G]

I problably didn't understand the concept of .NET in all details but as far as I know it is quite a simple task to 're-compile' the MSIL code of .NET applications (I think I read something like this on Borlands site because Delphi 2006 provides some features for this). If this is the case all .NET applications are opensource!
Now imagine you developed your own programm. You coded several month on it. Now you sell this produkt, someone buys a copy, recompiles it, changes the applications name and copyright information and sells it again as his own programm.
So who would code in .NET if this could happen?
This is why I think I'm not familiar enough with the .NET concept! Am I right or did I understand something wrong?

P_G

[Kambiz]

I wanted to switch to .Net, but I found it too slow. In my opinion, it is good for writing web applications only.