In my version of Bianca RealPlayer is in this repo:
## CANONICAL COMMERCIAL REPOSITORY (Hosted on Canonical servers, not Ubuntu
## servers. RealPlayer10, Opera, DesktopSecure and more to come.)
You can install with either Adept or Synaptic after adding or enabling this repo. Also in my Bianca this repo came with install [the only repo I've added is Swiftfox deb]. I can't remember if I had to enable it or not. To enable a repo just remove the # from the line with the actual repo url.
Linux Mint KDE, Ubuntu Feisty, Debian Lenny, and Gentoo 2007.0
AMD64:AMD64 X2 4800+:4x1GB DDR2
800:GeForce 6150 256MB:ASUS M2NPV-VM:2x320GB