My machine is WIN7 64 bit.
Could I use GFortran with Visual Studio 2010?
i.e. can I use the visual studio as an IDE for gfortran?
No, not that I am aware of.
You can of course edit the source code in Visual Studio as regular text files, but what would be the point of that?
If you want to use Visual Studio as an IDE, then you should buy Intel Visual Fortran Composer XE.
If you want to use gfortran as a compiler, then you should download Photran.