[oh one ls1 SS]

i had a problem last month that if my car sat over the weekend the battery would be drained by monday mourning when i had to go to work. i got a new battery 3 weeks ago and everythings been fine untill this mourning it was dead again. i didnt drive my car since friday afternoon. WTF! in march i was driving cross country and my car sat for a month and when i got back it started right up. now 2 days and its dead?? im not to good with wiring or electronics but is there any way to figure out whats draining it? or anyone that could lend a hand? thanks