That is a problem i had with my PS2 and DvD's.

I think this is how it goes. Game discs are certain manufacturer and the data is spread is different ways. For the most part games are fine and are the last thing to fail. You can see if it gets worse as your driver seems to start making more noise trying to fetch the data and failing a few times.
Movie discs, aswell as other discs are from several different manufacturers. The laser on your system will try to adjust to these new discs, but this comes at a price, as it will just de-adjust it further in time, the more different discs you use.

Eventually freeze ups come on games and eventually the system dies and cant read anything anymore without heavy strain and needs repairing. Unfortunely you cant send it to repair until the thing actually completely breaks.

That was the reason why i walked away from Sony after the PS2. It didnt leave me happy one bit. I thought they had worked their products out, but between you and what i see in a friends system, its depressing to see it still happens. That annoying slow death of the laser annoys me to no end.

I am planning on getting a PS3 and its gonna be a slim... but now im wondering if i should go for the super-slim...

There's two kinds of freezes with the PS3, first kind, is what I'd refer to as a 'good' freeze, all you have to do, like you said, push the power button once and the system will shutdown, you turn the PS3 on again and everything is fine. 

Then there's the 'bad' freeze, real bad, like. Where pushing the power once does nothing, I could push that button 20 separate times, and nothing. Then only way is to hold the power button in for about 20 seconds, the system will shutdown, but once once you restart the system it'll tell you ' Your PS3 did not turn off correctly. Your HDD is corrupted and needs to be restored. This may take 2-3hrs to complete', thankfully, it only takes 5 minutes. This is kinda freeze I get with the Blu-ray movies.

I have a Slim model, I'm using a pretty old HDMI cable, and I'm outputting it 1080p. I upgraded to a 1TB HDD about a year ago, and I wonder at times whether that was a wise decision.

I've had the HDD correpution check occur on what you call "good" freezes. I didn't know there  could be "bad" freezes.

I doubt your new HDD has anything to do with it since it should be reading it off the disk and not your hard drive. I really don't know what problem you could be having but I hope you can find a solution. I guess I should ask what happens when it freezes, does it still show an image? Play any sound? Is the disk spinning?

Thing is, I've been getting these 'bad' freezes more often since I upgraded my HDD. I get 'bad' freezes while I'm browsing the net. Not nice at all.

Yes, the image is still being shown, no sound, though. I'm not sure about whether the disc is still spinning.