Video card vs video capture card vs video editing card

What's the difference between a graphics/video card, video capture card, and video editing card?

All PCs have a video card which is also called a graphics card. The graphics card is what you plug your monitor/screen into. The video card fits into the AGP or PCI slot of the motherboard, depending on what type of graphics/video card you have. (Some cheaper PCs have the video card integrated into the motherboard). 

Video capture and video editing cards are additional cards. They  co-exist with the graphics card. Video capture cards are cheaper than video editing cards. They provide you with a socket for your camcorder. Some of them provide you with plugs for both analogue (S-Video/composite) and digital (DV) camcorders. With analogue capture cards you want to enquire whether they have both input and output sockets. (Digital connectors can both send and receive video clips, analog connectors do either sending or receiving). Video capture cards are generally bundled with some video editing software - nothing as beefy as Liquid Edition or Adobe Premiere - but more along the lines of ULead's Video Studio.

Video editing cards have specialist hardware built into the cards. This hardware is dedicated to video editing work (e.g. rendering and MPEG encoding). The better video editing cards are real-time editing cards. Many of them can handle in five minutes what a fast modern PC would otherwise take an hour. Most people see video editing cards as very expensive but we see them as free. Yes, free... :-)

When you pay £500 for a good video editing card the chances are that in addition to the card, cables, manuals etc you are also getting a professional video editing software package that would normally cost £500-£600 on its own, like Adobe Premiere making the real price you are paying for the card = £0.

Do I need to have a special type of video card in addition to the video editing card?

The video card has very little - if anything - to do with video editing. What the video card does is processes and sends video output signals to your monitor. Ideally you don't want the cheapest, most basic video card in a video editing PC. But you don't need the latest all singing and all dancing video card either.. Go for something in-between (unless you do also want to play high end games on this PC). 

However, it is useful to have features like dual-head support (also called twin head, dual monitor, hydra vision etc) which allows you to plug two monitors into your video card thus doubling your screen real estate. You'll enjoy working with videos when you can spread your work over two screens. You'll find you have a lot of little windows open and if you have two screen you won't have to keep shutting down some windows to see others. This saves so much of time it's unbelievable. With monitors becoming cheaper by the day there's no excuse to have only one screen. Another useful feature to have is TV Out via an S-Video socket. This allows you to connect a TV set to the PC to be used as a monitor.