Buy a battery like this one:
http://cgi.ebay.com/ebaymotors/ws/eBayISAP...&category=35617
This is the same battery I have in my car it is also in 2 of my friends cars. We have a total of 2 years of service on Brians, 1 year on Bens, and 8 months on mine. These batteries have worked just fine, the only time I have had to jump it is when I left the lights on. It also started after I left the dome light on overnight. I too have a 10" sub and a stereo, its been holding up just fine for me, the other 2 cars also have stero's and it hasn't proven to be a problem thus far.
Also get one of these:
http://www.odysseybatteries.com/pc680hd.htm
and some automotive terminals
http://www.odysseybatteries.com/accessories.htm#sae
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