[Ti] Ti harddisk question

[paulatx1 at aol.com]

My Ti800  Powebook is  3 1/2 years old now, and I have never had any 
trouble with the harddrive or CD drive.    Back in October, I noticed 
there was a "growling" noise coming from the computer.  It seemed to 
come and go; didn't seem to matter if I had been using the machine for 
hours or just a few minutes; didn't seem to matter if I was using the 
CD or not; didn't seem to matter if the machine was running really hot  
or not   [hey ...there were times  you could burn your legs through 
bluejeans if you had this machine sitting on your lap].   The growling 
continued and actually got more frequent and louder until February  
when it began to lessen in frequency and volume.   [Back in October and 
November, after being hit by Hurricane Rita, getting the computer 
repaired didn't seem anywhere near as important as  recovering from the 
hurricane.]
     I finally made enough money  to buy a replacement drive and I was 
going to replace the harddrive this weekend.  I think I have downloaded 
enough "how to" articles; I already own the torx screwdrivers; I have 
data backed up.   I bought an external drive case to slip the old one 
into  to carboncopyclone  the original drive back into the new one 
(after the new one is formatted).
      Here is what is bothering me:  I downloaded and installed SMART 
Reporter after seeing it mentioned on this list.  It says this drive is 
fine.    What if the growling noise I heard was not the harddrive?   
The drive in question is an IBM 40 GB.   Should I swap out the drive 
anyway?  (I have never swapped out a drive in a portable before.)   
Could it be the fan?   Would the CD  spin up  if there was not a disk 
in it?       Is there some other utility I could use to let the 
computer check itself?   If it is something like the fan, where is the 
fan?  Can I access it?
     Thanks for any advice.
                  Paula