I have always been led away from Hard Drive cameras and my brief experience with them has not been good. The best cameras in class seem to always be tape.
As far as Mini DV / HDV is concerned if you can stretch that budget to £600 you could pick up an HV20, which is HDV, but you would need a mac capable of handling the footage.
The best Standard Definition cameras around seem to be the Panasonic 3CCD GS cams. GS320,GS500 etc.
Imovie should have no problem with these at all.