Could anyone recommend a high speed PCI-bus SSP capable of 10Mbps supplied with suitable drivers to interface to a dotNET application?

* Data is sent via RS422 type drivers with differential twisted screened pairs terminated at both ends. 
* Data is accompanied by a clock with +ve transitions mid-bit. 
* Every 5 msec the data stream transmits 2000 bytes 
* Each byte will have one start bit, eight data bits and one stop bit (no parity).