Laptop Overheats only with old skool apps

[Frayo]

I have a Dell Inspiron laptop. Its semi-new (midway between new and completely obsolete at 1.5 years old)....

I have a lot of problems with it running old skool applications.

DOOM runs choppy...but I render it in 3-d using ZDOOMGL (modified) and it runs fine...even with awesome FX that make it look like it came out in 1999 instead of '93.

Heretic and Hexen and Strife are the same way... but with the ports its not a problem.

And also... my old skool emulators and video games...

And my new old skool addition... Fallout 2.

My computer will run them OK..not choppy (DOOM and its ID/Raven/Rogue counterparts are the only older things that run choppy)...
but they overheat my computer like CRAZY. I get only 30-40 mins runtime before something starts sizzling and my computer shuts down.

I dont know what it is...for Vice City and Morrowind and a few other newer ones like Sim City 4 (+ Expansion) can run for literally days on end without burning it.
To reduce some of the burden on the hard disk, I moved Fallout 2 to my external HDD, and it still overheats...only it takes a little longer.
I dont get it...
What can I do to fix this? Is it that my computa just doesnt want to face its ancestry or what?

[Vision_XD]

What model of inspiron laptop?

[Frayo]

5100