I would tell you to go to Adobe's Premier Pro page, but they seem to have as many answers as you would get here.
PPro message started from Anandtech
Myself, I just built a dual Xeon for Pinnacle Liquid Editon use along with Hash Animation:Master. Using the ASUS board (see Rigs) was a cheap option when it came to comparing Opteron duals vs Xeon duals. Either choice will be faster than most of the units you may have seen demos on. The SATA subsystem is not as fast as an add-on card, but it is fast enough for what I needed. I did opt for a Creative Labs Audigy as there are some suggestions, whether true or not, that the onboard audio could have issues during MPEG conversion for DVD.
You can spend lots of additional money on AV/DV solutions as well as NTSC real-time display. I cannot help you there in Premier. Check the Adobe Forum.
Edit - When you click the link, you can logon as Guest to get to the link