In windows 2003 and windows XP you could right click on an assembly (.dll) go to properties, click on the version tab and then you would see 3 different version numbers: Assembly version, file version and product version.
If you take that same file and look at its properties in windows 2008, you will only see file version and product version.
Is there a way to see the assembly version of a .NET assembly in windows vista and newer (without third part tools)?
No. Not from explorer. It is an intentional move by Microsoft (although I dislike it).
You can from powershell though:
[Reflection.AssemblyName]::GetAssemblyName('full-path-to\xxxx.dll').Version
Also if file version is not explicitly set it will default to assembly version.
Here is some info: http://all-things-pure.blogspot.com/2009/09/assembly-version-file-version-product.html