hi Mike
Since you are preferring for Linux platform , there are some good cards in the market.You can use Dialogic card for analog as well as for T1.if you need any card for Analog lemme know , I have some spare.
Another very good cheaper card you can use for linux is voicetronix card.
All the above are for service provider scenario but if youwant test in standalone application then quicknet is good.
Regards
Vik