Also, I'm debating whether I should buy DDR now and save up for a real-time card for later - if this DDR memory would serve well for editing video and then exporting to DVD I would be pleased to know. I was told that RDRAM would only speed up the rendering process slightly, but wouldn't make a difference if I had a real-time card.
Thank you for your support and insight on this matter!
Before you buy your computer, decide on your capture card. Then check the card manufacturer's website and find out what hardware is compatible with the card. For example, no VIA chipset motherboard is currently compatible with the RT.X100.