I want to replace the hdd on my macbook pro seeing as it has been complaining forever that it is about to fail. It has been failing the S.M.A.R.T test with a reallocated sector count of 2047 that has remained there since the problem started. 

I am tired of this and the work arounds needed to upgrade the OS and the incessant warnings to back everything up right now. Are there any things I need to know before I take the plunge and which brand of Harddisk would give me good service? Or I just buy any and go with it?