Laptops :: MBP Battery Performance Declining More Rapidly

I've been looking for some info on the older 2007 MacBook Pro battery specs and stats, etc., but have been somewhat unsuccessful. Lately my MBP has been draining the battery at a much quicker pace than normal. This machine is only a year old now (however CoconutBattery says the battery is 16 months old). Still, the battery capacity shouldn't have diminished too significantly. Before I restored the Mac and installed the Windows 7 Beta, I could average 3-4 hours on a full charge. Normally, I would keep WiFi + Bluetooth enabled, an external monitor attached, several USB peripherals plugged in, and the main display would be set to maximum brightness. 3-4 hours was pretty nice considering the amount of power the machine could have been using.

After I partitioned my hard drive, the battery life was cut in half on the OS X side. Windows 7 power management was even worse. I figured that there may have been extra disk activity causing this problem. After I finished toying with Redmond's new OS, I removed the Windows partition and moved on from there. I know after I removed the partition, I was getting excellent battery life initially. Once that short period ended, it went downhill from there. The battery meter has become surprisingly accurate as of late; in a minute or so, you can easily watch the percentages drop 1-2%, which appears abnormal. I can manage 3 hours on a single charge at best, but I usually get less. I decided to take greater care in cycling the battery, in hopes of nursing it back to health, so to speak. It doesn't appear to be working so well. Enabling WiFi and other peripherals only drains more power, but turning them off again adds only 5 minutes. So when I'm using several devices at once, I'm lucky to get a little over 2 hours. Turning off menu items and background apps does nothing either.

It's been this way for several weeks now, and yet, iStat, System Profiler, and CoconutBattery all report seemingly acceptable and consistent battery info: 86% Battery health, around 180 charge cycles, and the capacity is around 4700mAh (out of the original 5500) for now. The computer believes all is well. Performance says otherwise. I'd like to think that physically the battery seems to be okay. I've cycled and calibrated it several times. I have read reviews that indicate that Santa Rosa MacBooks with new batteries have averaged similar runtimes to the ones I experience now, but I know mine has usually bested all of the reported tests. It just seems wrong for the average runtime to go from almost 4 hours to 2 when the battery is (supposed to be) maintaining the same health level. I have AppleCare if it needs to be replaced, since this drastic change in usage time is very noticeable and counterproductive for me, but it could just be the computer (or me for that matter). Is this behavior normal for a battery of this age? What should I look into? If this is normal behavior I can live with it, but I would prefer to get as much out of the one I have.