So, not an easy job.
You could use a TDS (FreeTDS for example). It's quite fast, but when you get "heavy" record it may crash. --> avoid
You could use an ODBC driver. I'm gonna test the easysoft bridge. Hard to configure and a little bit slow. But very expensive.
* For the rest ... move to mysql !!!
Sorry, I've got the same problem and tht's the conclusion of 1 research's month.
Regards
Eric