Car Problems: Dead Battery Constantly?

I have a old 1991 Honda Prelude. My car battery always seems to die. I've had several batteries within the year 2007 and a brand new alternator in like december 07. After I put the alternator in, I got another brand new battery because the one before was dead. So new alternator and new battery. Everything was running great unitl now. I'm thinking the cold weather here did some damage to battery but completely drain it only in one day??? Yestarday I rode my motorcycle to work because we had nice(ish) weather, so I didn't drive my car the whole day. Now, this morning my car was completely dead, nothing but clicking when I turn the ignition. I'm thinking it could be a combination of cold weather and something draining the battery...I don't know though. Please Help...