UBUNTU 9.04 - DELL D600 - modem driver [DF]

I am looking for a Dell supplied modem driver.  I saw two for the Inspirion series and something about a custom version.  I'm moderately Linux savvy, but don't understand the back-ports topic.

Linuxant has drivers, but the 14.4K+ driver costs and I'm broke.

ANDY - Salt Lake, UT