Hi guys,
It's working now. The problem was indeed that in my game, the sims used the left side of the road. I have previously played the Dutch version, where as far as I can remember, this wasn't the case. Now, I've installed the English version off the same disc(s), and I hadn't noticed the driving on the 'wrong side'.
After reinstalling the NAM for left-lane driving, everything is working fine, except the U Drive It for the GLR on an avenue-track, but I'll try to get that working in the future.
Thank you guys for your help.