They both look like nice laptops for $500. I'm pretty sure you could say "overheating issues in the past" about any laptop dealer. It depends more on the cpu and/or graphics chipset for overheating than the brand of laptop.
Typically you can expect toshiba to make nice laptops for business. The specs are so close here though that I think you should consider two things:
Which one has a better screen? This is where most manufacturers skimp on budget laptops.
Which one is more aesthetically pleasing and nicest keyboard? If you're spending $500 it should be comfortable.
Personally I would check PCWorld.com. They test ALOT of laptops and have thorough reviews available in all price ranges.
Well... I have a Toshiba older model for 4 years now still works.... but I just bought an MSi for my daughter, she said it works great. I personally think this MSi laptop looks so awesome. I seen it at the OfficeDepot store it looks so nice... MSi make coputer parts so many years, now they make laptop computer - can't go wrong. IMO