What are the benefits and disadvantage of using either Git Extensions or TortoiseGit on a Windows Based OS?
I don't know GitExtensions, but I can share my experience with TortoiseGit (alluded to by marc_s's comment):
Pros:
Cons:
The problem with TortoiseGit is that people who worked with TortoiseSVN will think everything will (or should) work exactly like in SVN... and end up never really understanding how to work with git. As a personal experience, the company I work migrated from SVN to git after 2 years, and every single developer that used TortoiseGit ended up not really knowing what they are doing and sometimes screwing up their local repositories. In the end, they dropped TortoiseGit and spend time learning git "the hard way" (shell, msysGit on Windows) and everyone has been happy since then.
Conclusion: Just use msysGit directly and properly learn git. You will avoid many headaches in the future.