Dual Core oddness?

[snow patrol]

I have a opty dual core, but sometimes it doesn't quite seem right, most noticablely when i'm encoding divx to dvd-r. If i set the priority setting in Nerovision express to 'normal' and ecode, and then try to watch a film say at the same time, the film is jerky. I have to set the priority setting to 'below normal' for the film to be ok. Any ideas about that? I thought dual core would be able to encode on nerovision and watch a film or play a game smoothly at the same time?

 

[snow patrol]

thanks guys. I think NVexpress is dual threaded so it's running both cores and cpu usage is shown as rather high. But i still thought that if i then wathced a movie that windows would automatically sort it out and the movie would be smooth...