In my Opinion it Magician package,
If you have an rpm file for a package you wish to install, and if you cannot find a .deb debian package in any of the Ubuntu repositories or elsewhere, you can use the alien package converter application to install the .rpm file.
You can install alien itself from the Ubuntu Universe repository by adding the repository to your list of sources and doing:
$sudo apt-get update
$sudo apt-get install alien
Now it your UBUNTU is ready to Install the .rpm file
To install the .rpm file, you first need to convert it to a .deb file which can be installed on Ubuntu.
I assume that you downloaded the package to your Desktop (~/Desktop is the directory)
You can convert the .rpm to a .deb by using the following commands.
$ sudo alien -k name-of-rpm-file.rpm (for example : rdesktop4.5.noarch.rpm)
– This will convert the .rpm to a .deb.
– The “-k” will keep the version number. Otherwise alien adds a “1? to the version number.
$ sudo dpkg -i name-of-deb-file.deb
This will install the .deb package
Try reading the alien manpage for more details on how to convert other kinds of packages and the options available.