Let the search function be your friend. I suggest something like:
"+mod +4D" -you can use whatever number/size of cells you have: 3C, 2D, etc.
"+mag +lux"
The tricky part is that ppl 'round here don't call Mag's by their name. Look for Gag-lites, M@g, etc.
Please note that the thread is from November 2003, not 2004.
However, you'll find excellent reading material along the way.
Also the "Feeler" threads for the February and June WA / CA group buys are very informative with lots of discussion on various bulbs to use in M@glites.
WA = WelchAllyn
CA = Carley Lamps
are two bulb manufacturers the CPF community buys from.
How bright do you want it? I just recently took an old 2c I had from a sale, dropped in a KPR118 (radio shack 2 bucks) and 4 123's that were bleed down a little (reduces the insta-flash rate) and WOW makes it makes all my generic spotlights look yellow, dim and in need of a charge. Its got nothing a Thor though.