Compatibility Mode: 32-bit versus 64-bit

This post refers only to "compatibility mode", not "XP Mode".

I realize some apps won't install on 64-bit at all--such as those with 16 bit installer programs. Let's set those aside and consider ONLY apps that will install on both 32-bit and 64-bit Windows 7.

With that exception, imagine someone who is concerned about running some older apps on an upcoming Windows 7.

Is that person more likely to have success with "compatibility mode" if he also chooses a 32-bit install?

Or will he have identical success with "compatibility mode" on a 64-bit install?

I know people who are pondering this and who would never, ever even look at XP Mode or dual boot. They just want to be able to run their existing stuff.

Any insight appreciated.

Is there a semi-authoritative list of older or obscure apps known to fail completely on 32-bit compatibility mode? Or on 64-bit compatibility mode?

Thanks, Shawn.

I guess that leaves the question of 16-bit apps and I imagine most less than tech savvy types would only be guessing on that and that it has caused some consternation.

I do know that some 32-bit programs won't install on 64-bit Windows due to the 16-bit installer. Earlier versions of Photoshop for one.