This sounds strange, I have installed Debian on Dell R200s and fairly sure they use the same Network Cards as the PE2950s (only ever really installed CentOS, RHEL and windows on a 2950). I thought Debian came with this broadcom driver, however as far as I can see their are no drivers supplied for Debian on support.dell.com I know the Dell 2950s are being phased out by Dell and being replaced by their new R710s...
I am guessing the drivers you got were form this page, the generic Linux ones?
http://www.broadcom.com/support/ethe...etxtremeii.php