MacBook Pro - Mac firebird. Sell or repair?

hey guys, my mbp has been sold to me with a +- 13 minute battery, which I found out too late. Not sure if it's connected with my main issue of distribution. Any way my macbook is reaching temperatures which disable some of my peripherals ( correct spelling? ) and also my programs crash more and more often. After the first year of purchase I noticed "lagging" when I just played WoW in full screen, and the laptop got "moderately hot". This was due to the heat. Later on my mbp speakers shut down automatically. After a restart this problem was fixed. However this keeps reoccurring from time to time. Now i often like to have background music in itunes and playing the game. Which makes the sound AND the game to experience the "lag" feeling: music stopping then restarting and the game it self. As said before. And NOW... the **** mouse on the laptop itself has been "disabled". I am using an usb mouse now. And by the way this mouse "lags" as well during any application other than browsing. Also I have noticed that my macbook got considerably slower after the first one and a half year of purchase ( even with installing a clean new system). Still programs shut down and "lag". In addition some times the dvd drive doesn't eject my dvd disc or reads it poorly.

I was thinking should I just sell my mbp or bother to repair it? Reason is, because I would have to replace the battery to be able to use the laptop as an actual L a p top and I would have to check out what the **** is wrong with
the computer ( hdd i been told before on this forum could the problem ? ) which would cost me probably at least 250 euro all together. And i got "hand fingerprint" on the left side of the laptop cos im using it to type and the hand touches the surface every time, so it looks like somebody has been grinding it... I payed 1950 euro back then for the thing. I wonder what would be a better option..... I would be willing to switch to evil windows just to be sure that a system will be able to endure heat. However maybe It's an easy problem to fix? Ow and i did download iStat and it showed about 70 degrees temperatures overall. However the macbook was incredibly hot. At the bottom its untouchable and the palce where the speakers are located are hot enough not being able to touch it for longer than 1 second...