If you are running on a UN*X box you might want to try to use convert - it can do everything the ImageMagick module can (and more) and is just run on the shell - heck, you can even build a shell script for this. If the thumbnails need to be all of the same size, thinks would look like this:
#!/bin/zsh
a=`find $1 -type f | grep -E 'gif|jpg'`
for img in $a
do
echo "found : $img"
echo $img | perl -e 'while (<>) { s/(\w+)\.(\w+)$/$1\.thumb\.$2/; pr
+int $_ }'\
| while read thumb
do
convert -scale 50x50 $img $thumb
done
done
tested and works...
Sinister greetings.
"With tying hashes you can do everything God and Larry have forbidden" -- Johan Vromans - YAPC::Europe 2001
perldoc -q $_