To clarify cmonex's post, to get alt+tab redefined in CE 3.0 to function like in XP, you will NOT find it in Powertoys, but in Plus! for CE3. Program Switcher is the component of Plus! for CE3 that does the trick.
Excerpted from the Plus! for CE3 Readme
Program Switcher
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Using the Program Switcher, you can quickly switch from one program to another. After you install this program, reset your Handheld PC.
To use Program Switcher
- Press ALT+TAB to display the Program Switcher window.
- While holding down the ALT key, press the TAB key to switch to the next program. Release all keys to display the selected program, or press the ESC key to cancel the selection.
Note: While holding down the ALT key, press SHIFT+TAB to move to the previous program.