2008 MB with APM (not GUID), Clean install or Backup then restore?

Question

I have a mid-2008 Macbook that has the Apple Partition Map as it's primary partition. It appears as tho when I did a disk upgrade a few months back for some reason it got switched from GPT to APM. Not sure how, but that's a different topic. Since SL will not install over APM, I must go through a disk partition effort.
So, I'm fairly new to Macs but as far as I can tell my options are:
1. Backup disk (Time Machine), repartition, reinstall from scratch (same as 1), then restore from backup.
2. Clone disk to another same size disk, repartition original disk using GPT, then clone back to original disk, then install Snow Leopard.
Which one should I go with? Frankly, I'd prefer NOT to have to reinstall everything, is #2 it even feasable? If I restore from backup (time machine) is my computer restored back to its original state? all apps, bookmarks, etc?? A time consuming process is not what I'm looking for, so getting the system up and running ASAP is what I'm all about. I have a spare 500gb USB drive for backup I can use.
Since I'm not a mac guy by nature any guidance is appreciated.

Answer 1

netslacker2000,
Ah, but you didn't mention the fact that cloning was involved. Details are important! Yes, what you are describing is possible, and is in fact the method that must be used to create a "dual boot" external drive that will boot both an Intel machine and a PPC one.
But, let's clarify something right off the bat, so that there is no longer any confusion... A partition is not and will not have either a GUID format or an APM one. It is the partition mapping scheme that describes the partitions created on a drive, and thus it is a lower level aspect of the data written to a drive. The only exception to this is a rare one; it is the case that you find yourself facing right now. I'll try to explain as well as I can what is going on.
As I stated above, the mapping scheme- either the GUID scheme or the Apple Partition Mapping scheme (APM)- is the portion of a drive's underlying directory structure that describes what logical volumes exist on that drive. Intel machines can read either, but require a GUID mapping scheme in order to boot to the drive. PPC Macs can read either, but require a drive with the APM scheme.
However, since an Intel Mac is perfectly capable of mounting an APM drive, there is one way to "spoof" that Intel machine by a careful use of cloning. Under normal circumstances, a clone is made by reproducing one volume to another volume, or one drive to another drive. In this case, however, a drive has been cloned to a volume. The result is, in effect, like having a drive within a drive.
A volume cloned in this way will have its own partition map, its own volumes. So, in this way, one can "shoe horn" a GUID partition map- and any volumes that map describes- into a single volume contained on another drive. Is this at least a little clearer than mud?
So what do we do about it? Hmm, should be easy enough to fix. Let's stay away from cloning though, shall we? If I were in your shoes, I would first resort to restoring from Time Machine. I'm not sure how your current predicament may have affect Time machine, and your ability to restore the full system from it, but keep in mind that you can always just start fresh with a clean installation of Snow Leopard, using the Migration Assistant to pull your user data from the TM backup.
1) Boot to your Leopard install DVD (not the Snow Leopard DVD!). Insert the disk, then restart and hold the "C" key. When the installer loads, select a language, then open Disk Utility from the "Utilities" menu.
2) In Disk Utility, select your drive in the list on the left (select the drive, not the named volume that will appear indented below). Switch to the "Partition" tab. First, open the pull-down menu and change it from "current" to "Single Partition." Next, click the "Options..." button, and use the dialogue sheet that will appear to select "GIUD." Confirm your choice to dismiss the dialogue, choose "Mac OS Extended (journaled)" as the format for the new volume that will be created, choose an appropriate name for the new volume, then click "Apply." Quit Disk Utility to return to the installer.
3) Once back in the installer, go back to the "Utilities" menu and choose "Restore from a Time Machine Backup." Connect your TM backup drive, and wait for it to be scanned for backups. Select the backup you wish to use (I would assume the latest one), then wait to select a destination. This can take a couple to a few minutes, since the backup you choose must be "weighed" according to its size, to determine where it can be restored. When you are able, choose your newly created volume as a destination, then click "Restore."
If all goes as it should, you will end up restarting to the restored installation of 10.5. Yes, absolutely everything will be restored (all user data, all applications, etc., etc.). You can then prepare to install Snow Leopard over this restored installation.
You will be anxious, at this point, to get to the installation of Snow Leopard. Do not rush into this!! First, I recommend you allow your computer to completely re-index your hard drive. This is something that is done any time you restore from a TM backup. Watch your Spotlight icon at the right side of your Menu Bar. When it stops "pulsing," the indexing is complete and you may continue with your preparations.
Next, open Disk Utility, select your startup volume (the volume this time, not the drive itself) and click "Repair Disk Permissions." Allow this to complete. It may take quite some time; it usually does after a restore from TM.
You are now ready to install Snow Leopard. Insert the Snow Leopard disk, open it up, and double-click the "Install" icon. Follow the instructions, and you are on your way to a new version of OS X!
Scott