This script works on a PPC mini running Tiger 10.4.8 ...

…but is refused in an Intel mini running Tiger 10.4.10
Can someone please tell me how the script should be modified to agree with the Intel Mac?

tell application “SnapNDrag” to activate
tell application “System Events” to click menu item “Selection” of menu 1 of menu bar item “Capture” of menu bar 1 of process “SnapNDrag”

And just what does happen when you try?

For example, do you get an error message? What is it?
Does the script appear to run, but nothing happens?
Does your machine start emitting smoke?

That’s probably the most important thing - knowing what the error is will go a long way to explaining the problem.