The Portege is pretty crap at cooling in the first place according to
this review by Notebookcheck of your Portégé R830- they recorded temps of 90C after stress test benchmarking, and your laptop will probably go near there or even dangerously higher near 100. I wouldn't recommend mining on this at all if you still have a use for the laptop because of this- you
could mine with only some cores/threads, but the i5-2410M isn't a great CPU for mining in the first place and you'd be making maybe a few pennies a month after electrical costs.
If you really want to mine and don't need the laptop, I'd do something along the lines of what adaseb is suggesting and sell the laptop, then try to buy the best Radeon GPU you can get, in the 200/300 series. If you truly have very cheap electrical costs, those GPUs should still be able to mine at a profit even during these hard times in mining.