Strobes - and here's the fun part: I haven't used my light meter in over 2 years! The rules are the same as with film - using transparency, that is (digital has a very short latitude - blows out to white very fast, crushes to black or mud very fast).

Setup is simple in a product shoot (and architectural) environment - with film I had to wait, maybe take a few Polaroids, but film was a bit different so I still had to meter within an inch of my life.

Digital: Set up your lights, and any setting for your camera will merely be a starting position. FIRE!

Too bright - either close your aperture, or reduce the power of the light.

Too dark - either open UP your aperture, or INCREASE the power to your strobes.

It really is that fast to work with. Going for a specific effect - shallow DOF - open your aperture all the way to where you want it (2.8) and adjust your lighting - taking shots along the way will just show you where you are in the process. It's he ultimate Polaroid setup. Deep DOF - just the opposite, but same starting point - set your aperture to where you want it and work from there.

HMIs will run you some ugly money (couple grand for ONE light) - much more so than strobes, believe it or not. Calumet Travelite packages - $1,500 for a 3-light kit is a good starter. Alien Bees are good power and inexpensive, as are the modifying equipment and accessories.

I've been toying with the idea of getting flourescents - Kino-Flos or Lowel Caselights - for some of the stuff I do. Already I use LED pen-lights with gels on them for long exposure "painting with light" shots - they come out fantastic. And here's another beauty - you can do multiple setups with a locked-down camera and merely put them together in Photoshop (or like program) for a single shot with all the reflections where you want them, etc.

Hope this helps - good luck and have fun!
-Lew ;-)