I've decided to migrate to gcc-3.4.4, so I've emerged it, and switch the 
system to use it instead the previous (gcc-3.3.5-20050130).

After that I am supposed to update my system packages, so when I run
# emerge -va system
I get:
[ebuild N ] sys-devel/patch-2.5.9 -build -static 197 kB 
[ebuild N ] app-arch/bzip2-1.0.3-r5 -build -static 0 kB 
[ebuild N ] app-arch/cpio-2.6-r4 +nls 0 kB 
[ebuild N ] sys-apps/texinfo-4.8 -build +nls -static 0 kB 
[ebuild N ] dev-lang/tcl-8.4.9 -threads 0 kB 
[ebuild N ] sys-devel/gnuconfig-20050324 0 kB 
[ebuild N ] sys-libs/readline-5.0-r2 0 kB 
(...)
All with "N"!! I understand that this is not a update.. will the old 
packages be overwritten?
It doesn't make sense to think that I'll have duplicate apps... but just for 
being sure.. :)

In the middle of that list are:
[ebuild N ] sys-devel/gcc-3.4.4
[ebuild N ] sys-devel/gcc-3.3.6

This will compile anew gcc-3.4.4, but this time using the new compiler. 
That's the point, right?
The old gcc version is still there.. I haven't unmerge it yet, cause I first 
want to check if all goes fine..

So, should I go ahead..?

Thanks,
Fernando