Well There's no need to learn Java/Perl for .Net
in Fact its very good idea that you are now thinking of updating your skills now.
I assume you have knowledge of OOP and languages like C++ because that will help you get hands on C# .
One thing i would like to tell you is .Net and Linux are foe.
If you willing to learn .Net then learn it over windows platform.
Hope tis will solve yours issues