New Catalyst system, GT120 or HD4870?

[Mr_P]

To answer your initial enquiry:
ATI 4870 performs better than GT120. Nvideo 8800GT also works well if you require 2 x DVI ports rather than Mini-Display Port. There are other new cards on the horizon which should offer 2 x Dual-Link DVI ports.

I've had really bad issues in the past when capturing SDI - bad frame delay and buffering with Deckling HD Extreme - It may be able to capture almost everything!... but there are better cards out there. - Depending upon your requirement - take a look at Active Silicon LFG or Phoenix for Composite or SDI: www.activesilicon.co.uk

see movie:
files.me.com/simonpugsley/3t7u5e.mov

Simon