Welcome to CPF. Just my two cents. I would recommed a Surefire 6P bored out to use 18650 Lithium Ion Batteries with a Malkoff or Nailbender Drop-in. There are also many things you can do to "pimp out" the 6P like adding a bezel ring and a clicky tailcap as well. Check out CPFMP you find some great deals.
Surefire 6P,Xeno SS bezel,Moddoo Clipped Z59,Malkoff M60 on AW 18650 2900 mAh
Remember that these are rechargeable systems. There's no need to fiddle around with loose cells and no-name chargers. If you're looking for a reliable, easy-to-use system, stick with a name brand and get something that works out-of-the-box.
BTW, do you work in IT? Personally, I've found the Pelican 7060 to be best for IT work - the octagonal shape keeps the light from rolling around.