GRAHAMC  I just bought this product in order to shrink my Mac OS X partition and install Linux on my machine. I must say that I was a bit frightened by the less-than-stellar reviews on this page, but the product worked quite well.

Using the boot disc, I was able to compact my partition in iPartition (as the Help file warns, this can be quite slow if performed from a CD) and then successfully shrink it, all in a few clicks and keystrokes. Everything appeared to be pretty self-explanatory to me (though I did check help to make sure).

All in all, this is a great product and certainly a great value--if you check around, you will find that not only is this perhaps the cheapest of its type, but also that many similar tools run about $15-$50 more.  
(Version 1.5.2)