C#...
It's not really a C language though. C and C++ are dead as far as career paths though unless you write drivers or video games, but good luck finding any opportunities there. They won't let you put a foot in the door unless you have had previous experience.
C# is more accepted as business development though.
C# is a dot net language, which uses the dot net framework. It's not really much different than a VB.Net (which I'd also learn if you go that route as they are similar)... Basically C# is more C type syntax (semi colons at the end of the lines, etc) version of what you'd find in VB.net.
EDIT: I see alot of jobs out there using AJAX, ASP.net (which is developed in C# or VB.net) and Javascript these days (those combined). Web programming in general seems to be the highest demand last time I looked.