K Go Socket 939 amd 3500+ or 3200+ make sure it is 90nm if you go for a 3500+, Any Sli board will do for you if you just want it to work..Asus Gigabyte Msi. Get a Bfg 6800gt from, here for a very good price http://www.chumbo.com/Info.aspx?id=242673
I'm sure it is Pci Express its taken from the buy now link on the bfg site http://www.bfgtech.com/6800GT_PCIX.html
. As for the Hard Drives I's say get a 10000 Rpm one for you Operating system Western Digital Raptor 36.7GB or The 76Gb and as you are going to do video editing as stuff you need space so then get a Seagate NCQ sata drive they are very good 160gb or more should do for you. Case - get one with good airflow. Power Supply go with something with over 22A on the 12v line something around 450w or more, a good brand , as when you upgrade to Sli later you will need it. For the HDTV and video editing stuff, im not sure i don't know much about that but a seperate capture card or whatever you need should do, someone else can help him with this..
with that you will have a mean , Mean system
Hope that helps