well, if php is configured to NOT allow you running scripts outside of your home directory ( good for security, anyway ), imagemagick won't be allowed to run, since you are running the 'exec()' command...
hence, why using GD is what i'd recommend.
like i said, you don't gain anything HUGE by using IM, except for less memory use and performance on resizing ( rare )
GD should do fine for you, if your php memory is sufficient
