Old MacBook Pro, new HD, new Airport card
After eight or so years I ran out of hard drive space (who thought 70GB was too small way back then?). And dealing with the ethernet cable running through the floor from the basement was getting old - what's the point of a laptop if you can't use it on your lap top?
The repair was pretty boring. Printed out the instructions, taped the screws to the appropriate photos, followed the instructions to the end and then moved to the other side of the table and followed them backwards (not really). Hit the power button and everything booted up the same - only faster and from further away (no ethernet cable). I also now have a nice, "new", 70GB external hard drive to back up another old computer.
The only concern now is what the heck am I going to do with 500GB? (I know, I know...)
No problems, no issues, no story. Sorry...
Don't worry, be happy - upgrade now.
(One piece of info unrelated to ifixit: the new OS Lion won't run on the older Intel Core Duo - you need at least the Core 2 Duo.)