I'm guessing that since you say you need gcc that you are trying to install from source. With mandrake, you want to install rpms, which are the applications compiled for you and put into a single file with the extention .rpm
With mandrake, there is a tool called urpmi that will automatically resolve dependencies for you, and install all the rpms necessary when trying to install a single application.
Here is a link you may find very useful. As it states at the bottom of the page, "you might want to type urpmi.removemedia -a first, in order to reinitialize urpmi's setup"
After you run all the commands the page instructs you to, as root, all you simply have to do to install gaim is (as root):
To synch your local package database so that it contains the latest info on available software:
To update all the software on your system (with the exception of the kernel):
Well, I hope you find this useful. The plf (penguin liberation front) repository will contain alot of software that doesn't come with the stock mandrake install. You will get this new repo by following the directions on the link I provided near the top of this post.