Max speed of capture of analog data

Here's a system that samples at 1GHz:

http://www.ovro.caltech.edu/~dwh/correlator/index.html

I was at the Embedded Systems Conference class given by the designer (David Hawkins) and the system in the above link is being replaced by a Stratix II based system that will do 983 TMAC/s.

As far as the maximum bandwidth of the DDR-II and PCI-e, you can determine these pretty quickly through their respective data sheets. Although, maximum bandwidth, and real-world data throughput are two different things.