Macbook Overheating/Battery?

Hello,

This is my first post on the community boards so I would like to take a minute to say hi and thank you for looking into my problem.
Now to start, I have been having some trouble with my Macbook recently. I have been having an issue where I will be doing something very CPU/GPU intensive, them my computer just randomly shuts off. It has happened twice now, once when rendering video in Final Cut Pro X in Mac OS, and then just now again when I was playing Team Fortress 2 on my Windows partition. I did notice that the temperatures were a bit high (about 180-190 degrees) but I have never had any trouble with it shutting off before. I can be overheating because I know Macs have a failsafe built in to keep them from damaging themselves, but the thing that has been steering me away from this is the fact that my battery gets completely drained when this happens. I will be at about 80% charge while working, then my computer shuts off with no warning, and ALL the charge is dumped out of the battery. So I am not sure if it is just the normal failsafe or if it is the fact that my batter is going. I have been getting the Service Battery announcement as it just passed its 80% life mark but I still have a long way to go before it is completely depleted. If it helps at all, my setup is as follows:

Macbook Pro 13 inch 7,1 (Mid 2010 Model)

2.4 GHz Intel Core 2 Duo Processor

8GB DDR3 RAM at 1067Mhz

120GB OWC Mercury Extreme Pro 6G SSD

250GB 5400RPM HDD (Replaced optical bay)

Nvidia GeForce 320M with 256mb of shared Vram

OS: Mac OS 10.8.3

Dualboot: Windows 7 Ultimate 64 Bit via Bootcamp

Battery: 4331 mAh remaining of the designed 5770 mAh (fluctuates from 75%-83% life)

Battery cont.: 639 charge cycles, 33 months old

Case: Speck Seethru Satin snap on case (put this in because it may restrict airflow if it turns out to be overheating)

Repairs: Upgraded RAM, Upgraded to SSD, Replaced Optical Bay with mounting bracket and HDD, replaced the top case due to a broken keyboard from a cofee spill (about 9 months ago).

So that is pretty much the case. Doing something that works my computer hard, shuts off without warning, and all the charge is drained in the battery. It Even happens when I am plugged in. I have tried resetting the SMC and NVRAM, still no help. Just want to know if it is overheating, battery, logic board, or charging board.

Let me know your suggestions (whether is be taking it to the Genius bar or trying something at home) I am all ears. Keep in mind that I am pretty technical and know this machine inside and out so don't be afraid to ask me to open it up and peek inside, I have already had this machine completely in pieces.

Thanks,

Hank