The GeForce cards are more designed for gaming applications. The Quadro Series (e.g. FX 1500) are better suited to video-based applications.

Yes, the Quadro cards are worth every single, albeit, expensive penny! However, if you're looking to get more bang for your buck, or if you're like some of us that don't have a great big pile of cash, you can pick up a GeForce card instead.

I'm currently running Premiere Pro on a desktop with the Geforce 8500GT, and I get pretty good performance out of it. I'm sure I'd get better if I were to upgrade to a Quadro, but it's just not in the cards right now.

Regarding Vista 64. I'm currently running it, using a CS3 package that includes Premiere and After Effects. I'm also using the 8800GT card that a few people have mentioned in this thread.

Premiere and After Effects both run great, but that's not where the problem lies. It's the 8 series Nvidia cards that are the culprit. The drivers for Vista are flawed and cause the system to hang on a regular basis. The OS will recover, but the screen goes black for 5-10 seconds while its happening. A new update for Vista was released yesterday that was supposed to fix this problem (with all 8 series Nvidia cards), but I haven't had a chance to see if the problem is gone.

On another note, I've read several new articles on benchmarking Vista VS XP. The common conclusion seems to be that Vista requires more system resources, but is actually faster than XP. I guess it's a trade off.

I'm no pro on this topic, but based on my recent readings/experience, this is what I've discovered. Vista is getting better with the new updates, but it's still buggy and unstable. If I were you, I'd just stick with XP32 until Premiere supports 64bit.

So is your budget $1200 including a monitor? Or have you allowed $1200 only for the computer?

You're definitely going to want a graphics card in your machine. Like discussed here the Quadro cards are ideal, but a GeForce card will certainly be much better than the onboard video.

Do you plan to buy a pre-built machine (HP, Dell, Lenovo)? Or would you want to build one yourself?

Are you planning on editing any HD material? If so, you'll probably want a disk array of some sort to solve any dropped frame issues. Most motherboards have at least some sort of RAID support and are relatively simple to set up. A simple 2 disk array set up in RAID 0 (striping) can be set up for the cost of the hard drives which range between $70 - $150+ USD each.

The Q6700 processor is a good one, especially given the recent price break. Intel's new Q9300 and Q9450 are also good ones to look for.

If you plan to go with Vista, I would recommend 4GB of ram (yes you would need 64-bit to use it all). But since Premiere won't even use 4GB ram (since it is a 32-bit application), the only advantage here is that (theoretically) you can allow PPro to fully use 2GB of ram while your OS and other applications use the other 2GB.

A Quadro FX card will not speed your Magic Bullet renders. Note the compatibility list from the makers of the software:

http://www.rgsupportzone.com/system_compatibility