Just looking at the yahoo news on the left... :P
It seems desktop dual core AMD chips have been launched.

Someone correct me if I'm wrong, but aren't dual core chips slower at running simple applications (not prepared for multiprocessing) because each core is significantly slower than a nowadays chip?

The gain is in running multiprocessor ready software right? The kind that divides the work for both cores or is capable of running a full instance of itself in each core.