thing to consider in choosing between external or pci. (I used to work for BT Speedway! blech! and indeed they *are* rebadged fritz cards) ;)
Check the newsgroups ( uk.telecom for example ) as ISTR some talk a few months ago about the recent speedways using different chipsets, not all necessarily supported.
There is a supplier called Andrews and Arnold http:\www.aa.nu who have a rep for being linux-savvie
HTH Syd