Your updates sources need to be updated.
Go here and follow the steps:
http://easyurpmi.zarb.org/
Choose Main / Contrib and PLF packages.
The official packages as only 3 cd's. A lot more software exists. I have dowloaded all these sources mentioned above and filled 2 DVD-R. Within them they contain most software you will ever need in Mandrake all packaged up, including the not so legal ones that break patents contained in The PLF package. For stuff like the famous libdcss2 used for viewing encrypted DVD'.s.
Bu you don't need to download them at all. As long as your sources are updated on the right ftp site everything will be downloaded when you request to install it with urmpi, including all dependencies.