Looking at the css reveals:
/* ***** don't change the following ***** */
form { display: inline; }
label { cursor: default; }
.normal { font-weight: normal; }
.inlineimg { vertical-align: middle; }
which shows the problem.
Easiest solution would be to make all the images the same dimensions and pad the smaller ones. I've got a script here for doing just that in PSPX if Stuart wants to
email me the images I'll get it sorted...