Just abit of my thought ..
I went the Nikon route instead of canon.
Being a nikon user, i was hesitant to get an extra canon 5D just to do video. And luckily I did not cos I found out that the 5D does not support the 50/60 frames rate in 720p.
My alternative would be 60D which seems better than the 5D coz it does 50/60 frame rate which is useful when doing SDE .. for those who actually was in a time crunch you would know what I meant.What happens is
When you extent a time for frame rate 25/24 .. u lost frames and the video look jerky and unless u have some form of plugins ... anf in SDE when u use a plugin u need an extremely fast machine to preview and render the video .. given 3 hours .. that's a feat.
For me I am using a i7 quad core and I merely finished the SDE within 3 hours and that's with alot of planning ..
anyway ... back to the cameras .. I am using D7000 more these days for video compare to my D3s which some one mentioned above.
yes the D3s has better color, gradations and noise control .. however being full frame like the 5D, it tends to have less depth of field which I find in wedding videography is essential for me.
If I am using full frame, shooting the gate crashing or any other environmental shots , I would need to stop down ( like someone above mentioned 6.3 maybe). I need to increase ISO and in defeats the purpose of my 2.8s.
The D7000 being a crop sensor has abt 1.5 times more DOP compare to a full frame in usable frame size and I can still have the same amount of light coming into the sensor and thereby using a lower iso setting to get cleaner images.
If I do need artistic shots with shallow DOP, there's always my trusty 50mm 1.4.
Of cos besides that you will need some form of stabilizer. Get a lens with a build-in stabilizer, it helps on hand held. That is a start. Moving on further if you might need more fanciful stuff. as always there's the slider, glidecam, skate dolly, monopod and tripod etc.
While you can always rent these stuff, my take would be to own it. Nothing beats owning your own equipments as in between shoots there's always the "testing" work we need to do before the actual "job" we provide.
When you start owning these stuff .. you will understand why videographers charge the amount they do in the HD DSLR market.
Meantime start small, gears are what you need to do a job, workflow is the sequence you need to complete a job. You equipment and workflow must work hand in hand to minimize the stress when completing the shoot.
Hope this helps.
warm regards
FL