Normally you install software or deb packages on Ubuntu/Mint linux via Synaptic, Ubuntu Software Center/ppa, or an apt-get command from the terminal. In another hand, Fedora, centos, mandriva, and redhat support rpm packages.
Someday you have to install rpm package to your ubuntu/mint linux/debian box, there is a utility called Alien, Alien will converts packages from one format to another with ease.
Here is how to install rpm packages on ubuntu, linux mint, or debian
Install alien and all the dependencies it needs
# apt-get install alien dpkg-dev debhelper build-essential
To convert a package from rpm to debian format
# alien packagen.rpm
Finally, install your package !
# dpkg -i package.deb
For more info, use
$ alien -h