But today I try it again. Start Remote Buddy and it prompts to press 1 & 2, I do it, and voila - it works. I then shut it down and then re-start and it was a lot more difficult then. 1 & 2 wouldn't work (neither would red sync button). I tried to pair both simultaneously to see if one would pair (really scientific I know) and nothing happened. I restarted the computer and then tried again, no luck first time but eventually one paired but it did have to try a few times on each wiimote before latching onto one (and then saying Wiimote 2 unable to pair).

As far as my mac goes.... 
Machine Name: iMac G5 
Machine Model: PowerMac8,2 
CPU Type: PowerPC G5 (3.0) 
Number Of CPUs: 1 
CPU Speed: 2 GHz 
L2 Cache (per CPU): 512 KB 
Memory: 1 GB 
Bus Speed: 667 MHz

Even with the inconsistency (it works just not instantly every time), I am really really impressed with remote buddy (and my Wii as an aside - it's bloody awesome). And anyway, let's be honest, it's probably just me. 
Ben