Apple Menu --> About This Mac --> More Info...
System Profiler will open.
In the left sidebar, near the bottom under "Software
", click on "Applications
The main window will fill with a list of the applications found on your system. Click the "Kind
" header to sort by kind. Anything that says "PowerPC
" or "Classic
" will not work under Lion. Investigate whether the developer has released an upgrade for Lion compatibility.
You can also use a program like AppFresh
to help automate this process somewhat.