MacBook Pro 17" A1212 Hard Drive seems to be failing?

I have a Macbook Pro 17" Model A1212 purchased in 2006. I replaced the original hard drive 2-3 years ago with a Seagate 750GIG Sata 2.5". I am now experiencing problems with it waking from sleep with the lid open whereby it freezes, other times when I close the lid and return opening the lid I get the spinning wheel and have to force shutdown. Times when I simply move it from one location to another, I unplug the power cord, move it to another room to find it frozen.

It is old, I recognize that, but I'm having a hard time parting with a 17" display notwithstanding the sticker shock of a new one.

I think the hard drive is now done again, but before I throw good after bad, how can I tell if it's the hard drive or something like the logic board that's given up the ghost?

Any help would be appreciated.

Thank you,

Doug.