I am frequently asked about the various .Net framework versions floating around. As the .Net framework continues to go through its various revs the waters will only become muddier. Here is a quick overview of each version we have to date…

.Net 1.0 – This was the initial release of the framework which as of today only .Net 1.0 SP3 is currently supported by PSS. This only shipped as x86.

.Net 1.1 – This is a side-by-side release of the framework in which no dependencies on 1.0 exist. Hotfixes and Service packs for this version do not affect other framework versions. This only shipped as x86 and the latest Service Pack is SP1. This version also shipped inside the OS on Windows 2003 RTM but only in the x86 SKU. For x64 and IA64 versions of Windows 2003 there is no .Net framework installed by default. The x86 SP1 for Windows 2003 updates the 1.1 framework however it is SP1+ in that it does not have the same binaries as let's say a Windows 2000 machine with .Net 1.1 SP1 installed.

.Net 2.0 – This is a side-by-side release just as .Net 1.1. This version ships as x86, x64, and IA64. Windows 2003 R2 ships this version but does not install it by default. Using add/remove programs on any SKU will allow for installation. There currently is no service pack for this version. The x86 and x64 redist packages can each be installed side-by-side on a single x64 system.

.Net 3.0 – This is the first add-on framework. It adds functionality in the form of WPF, WCF, and WF, plus upgrades the 2.0 binaries by adding a few necessary fixes to make the new components function properly. This version shipped with all SKUs of Vista and has a redistributable package as well. The 3.0 redist package will install the 2.0 framework should it not be present or will upgrade an existing 2.0 installation. The x86 and x64 redist packages can each be installed side-by-side on a single x64 system. Currently there is no Service pack available.

.Net 3.5 – This is another side-by-side for 2.0 and 3.0 which adds functionality and updates the binaries of the previous two frameworks. This version has not been released and not much about it is public at this point but you can assume an x86, x64 and an IA64 version will continue to be available. You can probably also assume this will debut with Windows 2008.