yeah, the capture card is the most important thing. you have to decide what you need/want and get the card that best fits that critera as well as price range. the biggest difference in cards, until you get into pro cards like the dvRex or Targa is time. the raptorRT card will give you the same quality as the $1000 cards, but those cards offer a few more bells and whistles as well as greater RT capabilities. right now, canopus seems to have a stronghold in capture hardware. matrox's 2500 card i do believe isn't a full RT board. where the dvstorm is. pinnacle has released their x100 board. 3 cards i would look at right now are the dvStorm, proOne and x100. the dvRex prices you see on pricewatch.com are for addon modules. you will not get a full dvrexRT package until you hit about $2500 and that's most likely just the basic setup(dvrex board, dvrexRT board and software) you will also need 2 pci slots for the Rex. which is another concern depending on how many other cards you plan on having.
dual cpus are more of a benefit than raid. you'll see on average about 30%-40% faster rendering times over a single cpu. so what's your preference for cpus? dual systems from amd and intel put up comparable numbers. the biggest thing for most people is the cost. amd is a considerably cheaper route for dual cpus. i like tyan boards, or supermicro boards (for intel chips). i'm not into overclocking or anything so stability is the main thing for me. tyan and supermicro are known for the great stability and good performance in the server/workstation arena.
dv, being 3.5mb/s rate can be easily handled by a newer (7200rpm) single hdd. i have 3 drives setup in a raid0, to be honest i can't tell the difference between the raid and my OS drive. a couple limited edition WD drives (with the 8mb cache) would do nicely just on the mobo connectors.
for editing, there isn't anything else other than windows 2000 or windowsXP Pro.
so to recap:
-look at dvstorm <A HREF="http://www.canopus.com/ppm_dvstormse.htm" target="_new">here</A>, proone <A HREF="http://www.pinnaclesys.com/ProductPage.asp?Product_ID=471&Langue_ID=7" target="_new">here</A> and x100 <A HREF="http://www.matrox.com/video/products/rtx100/home.cfm" target="_new">here</A>.
-depending on workload dual cpus are defenitely a great asset for editing (in your case yes, it sounds like you'll be doing more than a "hobbyist" tasks).
-tyan mobos for amd/ supermicro for intel
-look at WD's limited edition drives
-win2000 or winXP pro
here is a good forum, bit more oriented towards these things:
<A HREF="http://www.creativecow.com" target="_new">creativecow</A>
other sites to check out with reviews and pricing:
<A HREF="http://www.videoguys.com" target="_new">videoguys</A> and <A HREF="http://www.guygraphics.com" target="_new">guygraphics</A>
also a good way to choose components after a capture card is seeing what's working for the people that are using it. all of those companies mentioned above have forums you can get on, most people will not mind at all sharing their setups.
THG; the Jerry Springer of hardware review sites.