install or upgrade newer or older gcc version

[saistain]

I have gcc version 4.0.2, and I need gcc version 3 to compile some software.

Here's where I'm not sure what to do - should I downgrade, or should I install a new gcc and run it separately?

For the former, how do I change gcc versions? I see a lot of guides that point to: Installing GCC - GNU Project - Free Software Foundation (FSF)
which only tells u how to do new installations

As for the latter, how do you deal with 2 versions of gcc? how do u specify one version over another?

Thx in advance

[xode00]

Look for something along the lines of compat-gcc-32. That should be a package that will install a compiler named something like gcc32, which will be a gcc3 compatible compiler.