I bought a book for Pinnacle Movie Studio 8 and it suggests a Pentium 4 3.06GHz (which was probably the fastest processor at the time of writing), 512MB of RAM, Windows XP Pro, a video card from either ATI, nVidia or Matrox with at least 32MB of RAM, a Direct-X compatible sound card, dual hard drives (one for the system, at least 40GB and the other for video, at least 80GB), a firewire card, a DVD burner and a gigabit ethernet NIC.
The book was written in (early) 2003, so if I were building a video editing machine now go for the fastest P4 "C" CPU that you can afford (forget overclocking the thing because it will most likely crash while rendering - it did with me). I chose a P4 3.0GHz "C", an Asus P4C-800 Deluxe motherboard and 1GB of RAM. Although Pinnacle Movie Studio 8 doesn't support hyperthreading, other, more advanced video editing software might (Adobe Premiere, maybe). As for the hard drives go, SATA is a good choice, SCSI may be overkill, but I personally don't think RAID is worth the hassle. I have two Maxtor Diamond Max 9 160GB drives connected to a Promise TX2-133 controller (along with two 40GB drives - a Maxtor and WD) and I have never had a problem capturing video. Let me rephrase that, I've never had a problem capturing DIGITAL video (no skipped frames). Capturing analog video I lost about 1 frame of video per minute of video, not too bad.
Unfortunately, your hardware can only take you so far. The task that takes up most of your time will be rendering of the video. Depending on the software/codec that is chosen and how complicated your video is, your computer can spend anywhere from 2 hours to 2 days to render, choose your software wisely.
In addition to the computer components, you should also add some sort of video editing software controller. I chose a jogdial called the Shuttle Express (from Contour Designs). The also have a more robust controller called the Shuttle Pro v2, but controllers are supported by the more popular video editing suites (Adobe Premiere, Pinnacle Studio 8, but not the Ulead products). You can also buy keyboards that are strictly used for video editing with colour coded keys for each specific function. Either way, these controllers can only help with your video editing chores.