"Having a dual-core processor makes ..."
"Having a dual-core processor makes a big difference to the performance available to you"
You use those words as the caption to a Windows performance graph which shows four CPUs. It also shows the current CPU utilisation as zero %, average CPU utilisation at well under 20% with a very very brief spike at around 60% on two CPUs, and the fourth CPU might as well not exist. Do you think this is representative of typical SFF/entertainment PC usage?
I've largely lost interest in GHz wars, but I'd have thought one single faster core would in general be a better buy than multiple slower cores with the same price and/or same total power dissipation, because most applications are still basically single threaded and therefore gain little benefit from the extra cores but may well benefit from extra GHz. Your graph shows this - the fourth CPU barely wakes up at all.
In a small form factor entertainment PC where fans are an undesirable complication, this consideration applies even more so than in standard desktop PCs.
Still, if you want to blithely repeat the industry's multi-core hype, feel free.