OOP on Linux: Best languages.

I've never programmed in Linux before and I suck without an IDE. What is a good IDE and good language to use for OOP on Linux. I've been learning C# recently and wanted to stick with it. Is there a good IDE that uses Mono natively?

>>3

Monodevelop is easier said than done, I've spend a good hour and a half and haven't been able to get Monodevelop to launch in debian. Thankfully there are plugins for Eclipse.