[xjsb125]

Processing power will be crucial if you are working with video, as well as system memory (RAM, not hard drive memory). If you can handle spending around or just under the $1000 mark, you can make a custom build that will hold up over time. Whatever you select for a video card should be able to handle 4K video. While it isn't prevalent now, eventually it will overtake 1080p, and you'll want to be able to handle that. I've had ATI video cards and always thought they did well. As for audio, I would stay away from Soundblaster. I can't remember the specifics on it, but I remember discussion that it may compromise the quality of your audio. A card with digital input, and fiber optic input, and your standard 1/8" jacks would give you plenty of transfer options. I have a HTI sound card, and have been very pleased with it.

If you custom build, you might consider a board that will support firewire, in the event you need to transfer miniDV, or if you use something like a Canopus A/D converter for VHS. It's old technology, and isn't on that many boards anymore, but you never know when you'll need it. USB 3.0 would also be something you want to have. Transferring those large files to an external drive goes a lot faster on 3.0. Another part to consider is the power supply. Make sure you have enough power to run the CPU, audio and video cards, hard drives, and anything else that may consume the unit's power. Needing 800W of power with a 600W supply will cause something to fail.

I hope that helps you out some. Good luck!