I used and still do some internal cards from Beronet, they have a PCIe
version on their site. HPS might know if it will work, it looks like a
new product.
http://www.beronet.com/content/category/10/38/91/lang,en/
External solutions: I use my asterisk at home with a Patton SN4634 ISDN
gateway: http://www.patton.com/. Difficult to configure, but if done
correctly, works rock solid. At home I had a cheap AVM Fritz v2 card
which gave me quite some troubles, would not recommend that. Replaced it
with the Patton and never any problems again. And you won't have any
issues with drivers, as you use SIP for your trunks.
Oliver