I own a late 2009 Macbook Pro, and it keeps freezing after OSX Lion installation.

Question

I own a late 2009 Macbook Pro, and it keeps freezing after OSX Lion installation.  I will post my computer's 'specs' below.  I installed Lion, from Snow Leopard, through the App store.  The first week, it worked like a dream, and was loving my brand new computer, or so it seemed.  I then began to run into problems, and I can't confirm this 100%, but I believe it was after I updated from 10.7.1, to 10.7.2. 
The freezes are sporatic at best, and cannot be narrowed down to one app.  I googled the issue about two weeks ago, and found a fix involving a temporary log-in, verifying the disk, restarting the computer holding CMD+R, and repairing the disk from there.  That fixed the problem.  For about three or four days.  From there I brought my laptop to Best Buy, where I purchased the computer (start the groans, my dad wanted the accidental damage, and he was paying, there was no argument).  My warranty there was still good, but all they were offering was to check my hard-drive, and possibly ship it out.  That would not be good for me, as I am a High School student, who works online. 
So I then decided to go to the Apple store, see what they said.  They said a bunch of people had this problem, it would cost a lot to fix, as I would need a new Logic Board.  This did not make any sense to me, as I knew it was Lion's fault, so why would they not make the L-2009MBP Logic Board compatible, and why are only a few people having this problem, well a lot more than a few, but I mean not everyone. 
So I asked a friend about it, and we decided to run a back up, and erase the computer, and re-install Lion.  Figuring maybe my data was corrupted during install.  This helped for a day or two, and happened again.  So this time, we backed up only files (music, pics, documents, etc.,) and did a fresh install.  I got my computer back last night.  Now, I am not saying that didn't help.  Previously I would have frozen about 18 times well writing this, but I have not frozen once (hopefully I didn't just jinx myself).  I have gone from about one freeze every 10-15 minutes (sometimes worse), to about one every 1-3 hours.  Which, let's be honest is still a lot. 
So, before I just decide to go and revert to Snow Leopard on my merry way, I ask, do any of you have any other ideas?  Or guarenteed fixes?  I know a guarentee is a hard thing to ask for, but I am desperate, my teachers are getting angry with me for not sending work, and I know this would help a lot of people.  Thank you to those who read through my whole spiel, and thank you to those who will help me!
[Ps, while I am somewhat of a noob, I know my way around a computer, so any help, or knowledge you could bestow upon me is awesome.  Especially DIY fixes.  (if your only advice is, don't buy a mac at Best Buy, don't bother commenting)]
Macbook Pro
15-inch, 2.53GHz, Mid 2009
Processor:  2.53 GHz Intel Core 2 Duo
Memory:  4 GB 1067 MHz DDR3
Graphics:  NVIDIA GeForce 9400M 256 MB
Software:  Mac OS X Lion 10.7.2 (11C74)

Answer 1

Once it is downloaded you need to restart the computer if it does not restart automatically. When it next starts up you should note a progress bar appearing below the Apple logo. When done the computer will restart once more. The new firmware should now be installed.