I use a Matrox RT.X
10 board with Adobe Premiere.
http://www.matrox.com/video/home.cfm
This setup won't qualify for Mercutio's "video editing on a shoestring" project, but it is also not horribly expensive. The RT.X card is comprised of analogue video interfaces and a built-in Firewire port for a IEEE-1394 digital video datastream. There are also video processors on the card for 2-D and 3-D video effects and digital filtering.
The RT.X10 and RT.X100 cards are relatively cheap compared to other similar cards, because there is a trade off: You MUST have at least a 2.0 GHz P4. The RT.X system utilizes the host system's microprocessor along with the processing on the Matrox card. This keeps the overall system cost down. What you get is a system that doesn't need to render very often as most video manipulation can be done in real-time.
Essentially, if you want the hardware acceleration that the RT.X board provides, you are more or less stuck with using Adobe Premiere V6.5 or Premiere Pro 7.0. Adobe and Matrox have worked together closely on the RT.X hardware / software. I can edit video for hours without problems -- this is using a Supermicro P4SGA with a 2.2 GHz non-HT P4, 1 GB RAM, Matrox P-650 video card, and either a Seagate X-15 15K.3 (Win2K boot drive) or a Seagate Barracuda V 7200 RPM ATA (WinXP boot drive) with a 120 GB or 160 GB Seagate Barracuda 7200.7 data drive.