I learned the hard way by buying a mediocre tripod/head combo and became very frustrated with it. Luckily I was able to sell it on Craig's List and recoup some of my loss. Definitely buy the very best tripod / head you can afford--even if it takes a while to save up.
After seeking advice here on CR, I went with the following:
- Gitzo GT-2531, Series 2 Tripod
- Really Right Stuff BH-40 w/LR (Lever release) plate
- Arca Swiss plates for my bodies and 70-200 II ring
My tripod-head combo is a mid-size making it sturdy enough for a xD body with a 70-200 II, and light enough for backpacking and travel.
Without a doubt, make sure your head is Arca Swiss compatible. I leave AS plates on my bodies permanently and use the RRS AS mini clamp (link below) on my Black Rapid strap to quickly connect/disconnect my bodies.http://reallyrightstuff.com/ProductDesc.aspx?code=B2-FAB-F&type=0&eq=&desc=B2-FAB-F-38mm-clamp-with-flat-back&key=it