I was browsing cards yesterday and I noticed the HIS brand... I've never heard of them before so I wasn't sure on their quality. Personally every ATI card I buy, I buy the ones built by ATI. The only exception was my last card which was a Powercolor X800 GTO, upgraded it to a X1900XTX
From what I understand
PRO < XTX
Pro was used a lot in the pre Xxxxx cards (i.e. 9500 Pro, 9550, 9600, 9600 pro, 9700, 9700pro, 9800, 9800 pro)
Also you must have a crossfire edition card to be able to run in crossfire (ATI's equivalent of SLI). I remember needing to have a master and slave card with an external dongle... but I belive with the advent of the X1950 Pro, ATI is re-doing Crossfire.