Is there any built-in, add-in solution for visual studio to compare two files and display result with differences? I could\'t find one...
Depending on your use case I'd recommend VisualSVN. You'll get the source control feature of SVN built into the VS IDE plus the ability to compare any source code file with any checked in version file from SVN.
It installs all the prerequites for you SVN (Subversion), TortoiseSVN, Diff, AND VisualSVN (The Visual Studio Integration).
It also has a nice quick windows installer for the SVN server which worries about apache etc. so you don't have to.
Essential for the non linux geek, it it not free but at $49 it is a bargain,
http://www.visualsvn.com/