ok, my last reply was less than clear, and Tichinde925 fogot something, so here Im gonna say it all right
you dont need to switch drives, there are other options (starfall for RF, backup-loaders for backups)
BUT to do so, THERE IS something you NEED TO KNOW:
(the unchipped one will work as normal when swapped.)
the CHIPPED one will be trying to force your PAL wii to load a "NTSC-J xy Optical Disc"
because that is what it forces every disc to read as.
so, two easy ways to fix this, but you must already have HBC running on your PAL wii:
-install starfall RegionFree and youll never even know the difference, but you'd still be running your chip on the wrong region
-boot your games throught the newest GeckoOS, you will notice the difference there though, obviously since sysmenu won't load them
BUT to REALLY fix, just use either of those two methods above, and...
Run the CORRECT REGION config/firmware disc for your modchip.
which I guess since you're installing the drive in a PAL system would be PAL region disc.
itll boot region free in GC mode with either method I described above, problem solved once you install
so to simplify....after you swap drives, you notice that no games will load
as long as you already have HBC installed, you can boot the newest geckoOS
and boot your new regions config/fw disc, and install the new firmware to your chip.