Problems with copy files to folder script

Hello,
I’ve been trying to write a script that will only copy a lot of files to a folder… easy enough, but the catch is that I will be making updates regularly, so I do not want to have to re-copy the files that already exsits in the selected folder. I think my method is good, I am just having trouble creating the check to see if file Blah exist in folder Blank.
Here is where I am currently at:

tell application "iTunes"
	set this_playlist to the view of browser window 1
	set allsongids to (tracks in this_playlist) as list
	set thePath to choose folder with prompt "Choose were you would like the files to be saved"
	set thePath to (thePath & ":") as string
	set thePOSIXPath to (POSIX path of (thePath))
	tell this_playlist
		repeat with i from 1 to the count of tracks
			tell track i
				set thesongid to item i of allsongids
				set songloc to (location of thesongid)
				tell application "Finder" to set filename to (name of songloc)
				do shell script "ls" & " " & quoted form of thePOSIXPath
				set theList to result
				log filename
				log theList
				if filename is not theList then
					do shell script "cp " & quoted form of POSIX path of songloc & " " & quoted form of (thePOSIXPath)
				end if
			end tell
		end repeat
	end tell
end tell

Currently, It overwrites the files every time. An ideas on how to get this running?
Thanks,
JO

You can simplify your script significantly if you have the Finder do the copying rather than relying on shell scripts.

tell application "iTunes"
	set this_playlist to the view of browser window 1
	set allsongids to (tracks in this_playlist) as list
	set thePath to choose folder with prompt "Choose were you would like the files to be saved"
	tell this_playlist
		repeat with i from 1 to the count of tracks
			tell track i
				set thesongid to item i of allsongids
				set songloc to (location of thesongid)
				tell application "Finder"
					try
						duplicate file songloc to folder thePath replacing no
					end try
				end tell
			end tell
		end repeat
	end tell
end tell

This also has the advantage of not having to covert to posix path names.

Thanks for the help! It works great.
I knew that you could use the finder duplicate, but I thought that using shell scripts would run faster when copying lots of songs. Is this not the case?
Thanks again.
JO