On-loan Tottenham youngster Taarabt scored a brilliant opener and won a penalty which Akos Buzsaky converted before Jay Simpson and Wayne Routledge scored to round off a fine Rangers performance.
It was the first time QPR co-owner Briatore had attended a match since the 'Crashgate' scandal in Formula One cast doubt over his future in football.
There was certainly no doubt about the quality of Taarabt's goal, which put the home side in front on 12 minutes.
The Moroccan rode two challenges before delightfully nutmegging Veliche Shumulikoski and curling a shot into the corner of the net from 25 yards.
Worse almost followed for Preston when defender Michael Hart's under-hit backpass was pounced on by Routledge, who was denied by keeper Andy Lonergan's block.
Routledge, who usually plays on the right flank, was deployed as a centre-forward - a switch that clearly unsettled Preston.
He reaped more havoc in the North End defence on 18 minutes before being thwarted by Neill Collins' last-ditch challenge.
And Lonergan again denied the former Aston Villa man when he sprinted from his line to save after Routledge had been picked out by a fine pass from Buzsaky.
Preston started the second half strongly and Chris Brown wasted a golden chance to equalise by blazing over from close range.
It was a costly miss because, on 63 minutes, Neil Mellor brought down Taarabt and Buzsaky steered home the resulting spot-kick.
Preston's fate was sealed when Youl Mawene misjudged Buzsaky's pass to Simpson, who finished coolly.
Routledge completed the rout by galloping towards the edge of the penalty area and smashing an unstoppable shot past Lonergan, before R's substitute Rowan Vine fired against the bar in injury time.