Using Emacs for C programming

[Kal]

Hello,

I'm new to Emacs and I'm looking for help to use it as an IDE. I've made 
some search on google, and found this tool : Xrefactory - 
http://www.xref-tech.com/xrefactory/more_c_completion.html

This seems to be very interesting. By the way, this plugin cost 399$ and 
it's closed source. So, is it possible to get something similar to this ?

I know the autocompletion key : M-/ but it works only on words already 
presents. For example, the first time I type "pri" and press M-/, it 
won't complete it to "printf". In fact, i'm looking for a way to get 
emacs working as Anjuta/Eclipse/Netbeans.

Why do I want to use Emacs instead of an IDE ?
- It's light
- I can use GDB with it, playing with Makefile
- Reading my mail
- etc...

When I saw that Emacs was able to do all that things, I've decided to 
install it and read his integrated tutorial. Now, I want to program, and 
look for a way to do it well.

Regards,

Kal