a little help here?

I need some car help. (Where are my brothers when I need them...)

Something is draining my battery and I think it's the starter. Or something ignition-ish. I had my car jumpstarted the day before yesterday (note: it won't be jumpstarted by an ordinary car, only by the AAA equivalent--maybe my battery is too big?) and then last night it wouldn't start! Now, I only drove it to the store and back (about 30 minutes each way) so maybe it didn't get charged enough...but it still seems wrong to me.

Now, and the last two times I had to jumpstart it (the first jump lasted longer...maybe two weeks), it doesn't turn over. It sounds a little like a machine gun when you turn the key. The lights and radio still work.

Any ideas? I could use the help because now I'll be dealing with people in two languages I barely speak--Russian and car.

p.s. Do you find it helpful or redundant to have the parenthetical remarks in a smaller font? I think both...but redundancy is bad and helpfulness is good. Oh! Just heard my friend Scott's voice in my head saying, "Kate, don't be helpful." Hmm...

Edited to add: The person in charge of vehicles at school and I had a brief pow-wow. He agrees that it's my battery, that it wouldn't start because the other battery was too small, and that I need a jump. He also said if I brought it to school he'd hook it up to a charger. Great! Let's hope this solves the problem.