Playing the old classic on Windows 7 gave me some trouble with speech being cut of about 1 second before it should have finished.
Read a few places about this problem and some suggestions about changing latency to 46 or 60 (in the deusex.ini file in the deusex/system folder), but this didn't work for me.
Changing from using Direct3D Support to OpenGL as the video device did.
Here is how:
- Open 'Deus Ex Safe Mode' from start menu
- Select 'Change your 3D video device'
- Select 'show all devices'
- Select 'OpenGL Support' and press next
- Accept settings suggestion (can be changed in-game later)
If this doesn't work for you, here are some forums with suggestions for how to get it to work with Direct3D:
http://www.ttlg.com/forums/showthread.php?t=99140 (since DeusEx runs on the Unreal rendering engine)