Well, if you want to experiment with .NET 2.0 I say more power to you!
The information below is taken from MSDN incase you prefer to read it
there[1].
The CLR uses two pieces of information when launching apps, one which
runtime versions are available and two, which runtime does the
application support?
Essentially what you want to do is change the app config files for the
applications which you want to force to use ver 1.x as opposed to ver
2.0. The runtime determines the appropriate runtime version to load
based on the results of the following process:
1. The runtime examines the <supportedRuntime> element in the
application configuration file. If one or more of the supported runtime
versions specified in the <supportedRuntime> element are present, the
runtime loads the runtime version specified by the first
<supportedRuntime> element. If this version is not available, the
runtime examines the next <supportedRuntime> element and attempts to
load the runtime version specified. If this runtime version is not
available, subsequent <supportedRuntime> elements are examined. If none
of the supported runtime versions are available, the runtime fails to
load a runtime version and displays a message to the user (see step 4).
2. If no <supportedRuntime> element is present, the runtime examines the
<requiredRuntime> element in the application configuration file. This
element is used only for runtime version 1.0 applications. If the
runtime version specified by the <requiredRuntime> element is present,
the runtime loads it. If the specified version is not available, the
runtime fails to load and displays a message to the user (see step 4).
If the application configuration file has no <requiredRuntime> element,
the process continues to step 3.
3. The runtime reads the PE file header of the application's executable
file. If the runtime version specified by the PE file header is
available, the runtime loads that version. If the runtime version
specified is not available, the runtime searches for a runtime version
determined by Microsoft to be compatible with the runtime version in the
PE header. If that version is not found, the process continues to step
4.
4. The runtime displays a message stating that the runtime version
supported by the application is unavailable. The runtime is not loaded.
Also, the runtime determines the available runtime versions by
enumerating the keys and values in the registry under
HKLM\SOFTWARE\Microsoft\.NETFramework\policy. Each key identifies the
major and minor version of the runtime. The values under each major and
minor key identify the build number. For example, the key
HKLM\SOFTWARE\Microsoft\.NETFramework\policy\v1.0 with a value of 3705
indicates that version 1.0.3705 of the .NET Framework is installed.
A directory with the same version number as specified in the registry
must also exist under the .NET Framework installation root. The
directory names are preceded with the letter v. For example, version
1.0.3705 of the .NET Framework would be installed in
<InstallRoot>\v1.0.3705.
Lastly, if you need to play with new products and not really mess up
your main machine and you cannot afford to (or don't want to) buy a new
computer then you can always run some virtual environments such as
VMWare/Virtual PC, etc.
HTH's,
Amit.
[1] -
ms-help://MS.VSCC.2003/MS.MSDNQTR.2005JAN.1033/cpguide/html/cpconDeterminingWhatVersionOfRuntimeToLoad.htm
