Thanks for help u0d102y. I will look into it.
"Why should Apple replace the part only if some people has nearly sounded issue with the unit?"
Apple should replace or repair the unit because according to the internet the issue is as common as the nVidia 8600gt issue in mcabook pro's.
Do a search on "Unable to list FireWire devises" and/or "mbp nvidia 8600gt" and you will see what i mean.
Apple has known about the problem for a long time.
http://support.apple.com/kb/HT1317?viewlocale=en_US
Not an easy to find unless you you know what you are looking for and not indicating how serious the problem can be or that the logic board might have to be replaced.
Think about it: On many Mac's the firewire is not working any more, just after the warranty is over.
It sounds to me like cutting corners more than anything else.