What model Macbook do I have?

I have an old macbook that I just bought and it needs a new battery. I have an old battery that I bought a while back for a macbook. The battery I have to replace it says model no: A1185, but i don't know if that is compatible with the macbook. Could someone tell me where to find this info? I took the old battery (the one that won't hold a charge) off the back of the macbook but couldn't find a model number on it. I also looked on "about this mac" and could not find it.

Download MacTracker from here Mactracker
When you open it, in the left hand column you will see "this Mac", select that, and then double click on the blue highlighted Mac in the main window, and a window will come up with the model and all the other info about your machine.

worked perfectly... thanks a ton
now the next question... it says the model of the macbook is 1181 but the model of the battery is 1185... will it screw up the mac if i put this battery in there?

It will be fine.

thanks for all the help:
okay, next issue... i've put the new battery in and its been "charging" for about an hour or so... but it still reads as 0% at the top of the screen... so you think this means my macbook has lost its ability to charge any battery whatsoever?

Firstly, when you say you have an old battery that you bought a while back for a Macbook, where did you get this battery, how old is it, and how much charge was it stored with?
Did the Macbook you just bought have a battery, and if so, what was happening when you charged it?

Also, have you tried resetting the SMC?
Intel-based Macs: Resetting the System Management Controller (SMC)

I bought a battery on ebay a few months back when I thought I was buying a macbook from another guy with a bad battery macbook. It has sat out for a few months but it only shows having 3 cycles in the "about this mac" page. It was new as of a few months ago, then sat around my desk until trying it on this other macbook.
This macbook that I am currently trying to get working did have a battery with 325 cycles on it. It was not charging according to "about this mac."
When I put the new battery in, the battery icon at the top of the screen has an "X" in the middle.
I just reset the SMC (or I followed the directions on how to do it, I have no idea if it worked or not cause there is no mention of a chime or ding or anything to let you know it was successful).
Any other thoughts?

I suspect that the ebay battery is dodgy, and your battery with 325 cycles has done it's dash.
My thoughts are that you should get a battery from Apple or MacBook 13" White Laptop Battery High Capacity by NewerTech for all MacBook 13" 'White' models up to 2.13GHz

shame... i suppose i could try this battery on someone else's macbook and if it charges on it then do we know it is something wrong with the computer at that point?

I was going to suggest if you have a friend with a Macbook, that you try your battery on theirs, and vice versa, including trying swapping chargers.