Replacing a Powerbook Hard disk

It sounds to me like you have the technical skills to do the job. Two main points:

1. Must have the correct tools, and
2. Keep some kind of bin/container setup to completely organize the screws etc that will show up, bearing in mind the specific order they materialized. For example, some are slightly longer/shorter and you don't want to mix them.

Separate items slowly; there may be hidden clips holding cables to components.
Take your time, others will chime in here with their experience.

Good Luck,

Joe

You're correct that the drive you listed will work. You want a 2.5" hard drive that has a parallel interface. Serial interface or SATA drives will not work. Speed of 5400rpm in new parallel interface drives is industry norm today. Getting a larger size than you've got today is a good idea too.

The ifixit instructions lay out what needs to be done pretty well. As Joe mentioned, it helps to have cups or cupcake tin to organize all the screws you'll take out (First time I replaced a hard drive, I used one cup for each step). It helps to buy a new phillips screwdriver if you don't have a small one in good shape. On my system, when you get to the step to remove the two screws by the screen, which is step 7 for your system, my screws are allen hex and not torx - you should look at yours before buying a torx tool.

The other thing to be careful with is the plug that goes into the back of the hard drive. It's not a big plastic plug as you'd find on a desktop system, so you want to wiggle it carefully to detach it. When you reinstall, make sure that the plugs on the logic board are completely replugged and tape pressed down to hold them. Since it's annoying to button the whole thing up, put all the screws back in, and find out it won't boot, you may want to put it back together, and power it up to ensure all the plugs are in correctly. Then shut it down and put all the screws in. And don't over tighten the screws.

... My powerbook is now only recognising the RAM in the upper slot ....
Would anyone have an idea as to why this could have happened?

You may know the lower memory slot failure is an issue that affects some Powerbooks. Apple had a warranty repair program on a subset of 15" models affected, which has since expired. Assuming you were careful and didn't do something to the logic board or memory compartment, I'd suggest it's just bad timing.

Solutions are to live with 1GB in the upper slot, try one of the companies that says they can repair it (scan the discussions for recommendations), or replace the logic board (Apple ~$350 thru Apple depot, ~$750 in store) or do it yourself.

If the Powerbook is working well for you, it may be worthwhile to take it to the Apple store and let them send it to the Apple depot for repair, rather than buying a new system. It runs around $350, although if the case is banged up it's more, as the Apple depot will fix whatever needs fixing to put it back into almost new shape. We recently sent one in with a bad logic board, and they replaced both the logic board and battery.

Glad it's working for you. You can always monitor the page ins/outs in the Activity Monitor to see if there's any severe memory constraint.