Personally, I hate the Dawn of War 1 voice acting.. particularly with the most recent addition, Soulstorm. Nothing shows just how bad the acting, and scripting, became more than the Beakie's Commander Boreale during his "motivational speech" when their fortress gets attacked.
Allow me to show you exactly what i mean... Complete with accent. These two also happen to be my favourite non-Ork quotes, shows just how bad some voice acting can be.
QUOTE (Beakie Commander Boreale)
Spess mehreens! Todeh the enemeh is at our doar! We know our duteh and we will do eht. We fight for our honour, as bluhd rahvens, as spess mehreens, and we fight in the nehme of the Empra!
And if we die this deh we die in gloary. We die hearoes' deffs - But we shall nort die - No, it is the enemeh who will tehste deff and defeat!
As you know, moast of our battle brothers are stehtioned in spess, pruhpeared to deep strike! Our perimeter has been pruhpeared in the even theht our enemehs should be so bald and foolish. We have plehced numerous beacons, allowing foar multiple, simultehneous, and devehstehting defensive deep strikes.
The codecks astartees nehmes this maneuvah Steel Rehn. We will descend upon the foe, we will ovahwhelm them - We will leave none alive! Meanwhile our ground foarces will ensure full defense of our headkwarters.
We are the spess mehreens! We are the Empra's fureh!

Best part though would have to be when he's krumped at the end.
QUOTE (Beakie Commander Boreale)
Spess mehreens! We have fehled the Empra!
If you'd like to see the scene for yourself...
Click here to see for yourself.Need i say more?