Thanks! Would I have to re-install the software (assuming it is compatible of the newer 10.11.6 El Cap)?
Sorry if this is a newb question. I'm a linux user (seems similar to the OSX).
This is, what I would do (have done) and
@eyoungren and
@B S Magnet already suggested: either an upgrade to SL (more browser-options) and/or macOS-Patch (Sierra/HighSierra/Mojave) and optionally a dual-boot drive.
(I personally think, the dual-boot option is the better one, because it leaves your current well-functioning Leopard-configuration untouched.)
- get a >= 250GB SSD for 30 bucks and an external USB-housing for about 10bucks
- connect your SSD within the USB-case and create two partitions on that SSD with DiskUtility: the last partition gets 12GB, the 1st one all the rest. (if you're gonna keep Leopard/Rosetta, then devide the first portion into two partitions: one for L/SL, the other for the macOS upgrade)
- get Sierra/HighSierra/Mojave-Patcher and install the patched macOS version onto the last (12GB) partition of the SSD (for first installation and for further recovery)
- clone-copy your internal drive to the external USB-SSD-drive with CarbonCopyCloner. (For the dual-boot-option make a clone-copiy of your system onto each partition: one for Leopard, the other for the macOS-upgrade)
- put the SSD into your MBP4,1 (the original drive will stay untouched as a backup-drive and goes into the USB-case for further clone-backups of your Leopard/music-production-partition)
- boot from the last Sierra/HighSierra/Mojave-patcher partition and install patched macOS onto the the Leopard-partition to make the upgrade to patched Sierra/HighSierra/Mojave. (If anything fails, you have your original disk still in a save place and may clone-copy it back to your internal SSD).
For the dual-boot-option the SSD starts with Part1:Leopard / Part2: Leopard / Part3(12GB): Patcher.
(If you want to have the option to reduce the SSD to only one partition, it's important, that Part1 is the partition, that will remain after consecutively deleting Part3 and Part2.)
Keep HFS+ as the file-system for the patched macOS-partition (this should be the standard procedure w/o anything necessary to be done), so you can still access the drive/partition with the upgraded macOS whenever you've booted into Leopard/SnowLeopard.
- after installation reboot into the patcher(12GB)-partition and complete patching the upgraded macOS-partition.
- reboot into the upgraded Sierra/HighSierra/Mojave-Partition.
Voilà ...
Now you should have a 32bit-compliant macOS with HFS+ file-system (compatible with pre-APFS both intel- and PPC-Macs) and optionally on the second partition Your untouched Rosetta-compliant Leopard configuration.
The last (12GB) partition keeps the Patcher-installer for any reinstallation/repatching-procedure (that's useful, if you ever happen to run into a macOS-update and need to repatch the system. Alternatively you can create a USB-stick with the patcher and than delete the tiny portion at the end in order to increase size of the partition, that is just in the location before it)
I've been through this routine several times and it's awesome to see, how
@dosdude1 made this happen!