scripting Quicktime to convert images to jpg

Here is a droplet that I am working on to have Quicktime translate
still images generated by iMovie into JPG images that can be imported
into iPhoto.

on open (theList)
tell application "Finder"
repeat with x in theList
if {"disk", "folder", "alias"} does not contain kind of x then

tell application "QuickTime Player"
set this_image to open x
export this_image to x as picture using most recent settings with
replacing
close windows
end tell

set thefilename to (item x of theList) as text
set the name of file thefliename to thefilename & ".jpg"

end if
end repeat
end tell
end open

This droplet fails when I am trying to rename the files. I would like
to change the names of the files from "Still 01" to something like
"myname 01.jpg". I am having problems just adding ".jpg" to the
original name. I thought this would be simple.... not simply
impossible.

Can anyone help? Thanks.