Since this deck will digitize analog tapes or capture digital tapes directly for you, the best connection is the firewire (IEEE-1394) port. Premiere Pro should be able to capture directly from this port. Almost any firewire port, including the one built into most motherboards, should work fine, as it only has to transfer the digital data from the deck to the computer.
Thank you for your reply... People say I should buy Quadro SDI Capture Cards or such, which will cost literally thousands of dollars.
So, if almost any firewire card would work fine, what would be the difference? The picture quality? Why would people go and buy those capture cards instead of buying a firewire card for like 10 dollars?
The only reason to buy a capture card is to convert analog video into digital. Your digital Beta tapes are already digital. You just need to transfer that "data" to your computer. Your tape deck already does that for you. All you need is a regular IEEE-1394 port and a cable to transfer that digital video to the computer.
You could output an analog video signal into a fancy capture card, but that would be a degraded version of the original. You'd be converting from digital to analog and back to digital. The best quality is the original digital.
I still have a computer with an RT.X100 card, which I used to capture VHS and Beta analog video. Since I've upgraded to HDV, I haven't had much use for it.
A future upgrade you should consider is upgrading to CS5 running on 64-bit Windows 7, which will take advantage of your Quadro FX3800 card with its Mercury Playback Engine, speeding up timeline playback and rendering.