Thanks BarneyFife, are there any camera's which have a higher success rate (ie they usually come with a firmware which works with CHDK) Sorry for all this fuss, I just reallly really want to get this working and I'm probably going to end up ordering online on amazon, so I want to be pretty confident before I buy!
Also I've just noticed that on the main page of the wiki it describes the firmware needed for the A570. However all I have found on the internet is a A570IS. Is this the same camera? And is it likely to get this one to work?