Hi,
GLIBCXX_3.4.9 is required by gcc4.3. See for example [url=https://root-forum.cern.ch/t/root-5-22-on-slc5/7644/1 post[/url] to see how to setup your environment (if you have access to afs).
And yes, you can also build from source with your local gcc4.1 (or any other version), but if you are member of an experiment, this is probably not the way to go (you should ask people from your group)
Cheers, Bertrand.