As for the computer question, the main criteria is getting an Intel chipset, a 2.4 or better CPU, 1gig of RAM, a very good video card and two harddrives (I prefer Maxtor 7200rpm).
Your best bet is to buy from a local "mom & pop" type computer shop.
You should be able to have everything built from between $600 and $1000 (not counting software). If you're within driving distance of Dallas, and want to ignore my local purchasing advice, checkout their First Saturday Sale. That's where I bought my system. More info at:
http://www.rs-kit.com/articles/
As for hardware recommendations, check
http://www.okvideoguys.com (no relation to my OKVideoGuy.com). They might be a good place to get the video card from also.
As for getting video into the computer, you're apparently asking about RCA cables, so I suppose you have an analog camcorder? (Hi-8 or something?) Hopefully your camera has an S-Video jack because you'll get much better video quality that way.
If you do need analog capture AND you want inexpensive editing software that is easy to use and will let you do some pretty neat effects, then you can get everything in one package with Pinnacle's Studio 9. Be sure and grab the box with the PCI AV/DV card if you have a desktop computer. You'll need the USB box if you're using a laptop.
If you have a digital camera, then you need a firewire card and cable. I bought mine for under $30 at Best Buy on sale, but they usually go for about forty or more. Try TigerDirect.com for good mail order prices.