64-bit compliant ddk samples

I am playing around with the samples in the WDK or DDK. In the HTML document, it
says "this is 64-bit compliant". Does this mean that it won't run on my
32-bit Windows XP system? I tried to install 64-bit compliant Msplotter
sample on my machine. I could not see it after a successful installation.

On the other hand, a 32-bit complaint software can run on 64-bit system. Am
I right?

I am wondering which option I should change so that I will build a 32-bit
compliant samples so that they can run on my XP.

Thanks in advance!

Correct, 64-bit compliant code, will not run on a 32-bit machine.
32-bit code, runs on most current 64-bit builds, but not natively. It runs through an emulator, on windows platforms, it's called WOW, just as 16-bit code runs on XP, but again, not natively.

Most of the time, the code will run as expected; newer versions of visual studio have the ability to code for both 32-bit and 64-bit compliant, and you can just choose which one you want to compile, allowing you to actually compile two separate exe's, one that runs 64-bit native, the other that runs 32-bit native.