It is not documented on the web site and people seem to be having problems setting up the framework. Can someone please show a step-by-step introduction for a sample project setup?
What Arlaharen said was basically right, except he left out the part which explains your linker errors. First of all, you need to build your application without the CRT as a runtime library. You should always do this anyways, as it really simplifies distribution of your application. If you don't do this, then all of your users need the Visual C++ Runtime Library installed, and those who do not will complain about mysterious DLL's missing on their system... for the extra few hundred kilobytes that it costs to link in the CRT statically, you save yourself a lot of headache later in support (trust me on this one -- I've learned it the hard way!).
Anyways, to do this, you go to the target's properties -> C/C++ -> Code Generation -> Runtime Library, and it needs to be set as "Multi-Threaded" for your Release build and "Multi-Threaded Debug" for your Debug build.
Since the gtest library is built in the same way, you need to make sure you are linking against the correct version of it, or else the linker will pull in another copy of the runtime library, which is the error you saw (btw, this shouldn't make a difference if you are using MFC or not). You need to build gtest as both a Debug and Release mode and keep both copies. You then link against gtest.lib/gtest_main.lib in your Release build and gtestd.lib/gtest_maind.lib in your Debug build.
Also, you need to make sure that your application points to the directory where the gtest header files are stored (in properties -> C/C++ -> General -> Additional Include Directories), but if you got to the linker error, I assume that you already managed to get this part correct, or else you'd have a lot more compiler errors to deal with first.