First of all, hi to all you nice folks from eastern europe. I went there this summer, and found everyone to be really friendly. Even got me a few pen-pals there...
Second, about C-compilers...
Well, gcc is at the heart of linux. Referring to the 'Borland C'-part of the subject, you will really have to learn to see software in a new way. With Linux, software is free. The OS. Tools. Applications. Everything. We don't use cracks, serials or any of that sort of things.
In stead we are blessed with a multitude of choices. Often all too many to avoid confusion along the lines of 'Which one is best?'
This is good.
But why gcc, then?
Well... GCC is the most widespread code generation tool on linux. Not necessarily the best, but the one most likely to provide you with a steady well-supported base known to many people - whom you can then ask for support, easing your work considerably.
About graphics...
Dunno much about this issue, but i've managed to get a graphical RAD tool to work under X. Sort of a 'Visual C for Gnome'-thing. Look for Glade (GUI builder tool) and Anjuta (IDE). As i recall, they work together.
For inspiration, look here:
http://eddy.writelinux.com/part2/
And then to the point of free software: Once you're all settled and start cranking out one cool app after the other, give something back to the community. Write some free software. You'll feel good about doing so