you need glibc 3.4.x for that library to be installed. You have 3.3.x ... hence the problem. I would exercise caution if you intend to update glibc, since many, if not all linux applications will not function if not installed properly.
A full "yum update" or "up2date -u" would upgrade all necessary packages and dependencies on your system without much harm - but you should still be very careful - you do not want to start installing newer packages with missing dependencies or references to old libraries. I believe up2date has a "rollback" feature you can enable. If you look that up and enable it properly, you can attempt to upgrade packages and roll them back if something goes terribly wrong.
Just my two cents