NiCad and NiMH are very similar but each have their own pros and cons, i.e. NiCad is marginally better in cold weather, NiMH has a greater energy density, etc... read up at http://www.batteryuniversity.com/partone-3.htm
One should also note that there has been a large amount of development of NiMH cells in recent years. High end NiMH cells (GP3700, IB3800) can push more current than the best NiCad.

There's a good bit of info about Lithium based batteries here: http://www.batteryuniversity.com/partone-5.htm

Calvin, airsoft mini batteries are 2/3A cells, butterfly, ANPEQ (generally) and AUG batteries are A cells, and large batteries are SC.

If you have an RC charger already setup to charge Li-po's, check these out:

http://cgi.ebay.ca/ws/eBayISAPI.dll?...ayphotohosting

15/16"X1"1/16 X 3"7/8 long - 11.1V, 2000mah, not bad for an hopped up gun :mrgreen:

Marco P.