Here is how I got my Americas Army Screen shots working this was done with a clean install of Nvidia driver(winxp_169.21_whql) with RivaTuner V2.06.

I even tried it again to see if it was the only thing that fixed it as nHancer didn't fix it with the winxp_169.21_whql driver for me.

Here is how I found the fix.
After having no luck with nHancer I tried RivaTuner but nothing I tried worked & after it started to BSOD on start up of Americas Army I didn't want to try anymore settings so I reset it & after a reboot to see if it fixed the BSOD it fixed both the BSOD & the screen shots.

So once you have done it restart & try it.

UpDate1: Once its fixed you can change your profile settings with the Nvidia control panel if needed.
UpDate2: updated info with links.