This should work, just change the first line ("~/Desktop/untitled\\ folder") to the directory with your jpg's.
(note the "\\" for a folder name with a space)
You should work on a copy, not the originals, so first copy all your jpg's to a temp folder (i.e. create a folder on the Desktop), and if the files are renamed properly, then erase the old jpg's and copy the renamed files to the original location. Also, you should backup your files first)
set theDirectory to ~/Desktop/untitled\\ folder"
tell application "Microsoft Excel"
tell active sheet
tell used range
set rc to count of rows
end tell
set theList to get value of range ("A1:B" & rc) as list
repeat with theItem in theList
try
do shell script "mv " & theDirectory & "/" & quoted form of item 1 of theItem & space & theDirectory & "/" & quoted form of item 2 of theItem
end try
end repeat
end tell
end tell