I have an executable that defaults to 32-bit. It doesn't have source code and I want to keep both 32-bit and 64-bit frameworks on the system. Is there a way to make that executable run on 64-bit .NET framework instead?
use the corflags tool to flip the '64 bit is okay if available' flag
This blog post explains this with examples and some further links.
If you have the source code recompiling with anything VS 2005 and over will allow you to change the settings to make it willing to run as 64 bit.