Nope. Something of a back-pedal by me, shamefully.
First off, Dell quoted a delivery time of 12th December - very poor.
Then I took dclayton's advice above and investigated the ASRock a bit further, and ended up cancelling the Dell order and going for the 330HT-BD instead, saving myself just over £200.
It arrived yesterday, I installed Win 7 Home Prem (x64) painlessly last night, along with nVIDIA drivers. So far it seems to work flawlessly. It's responsive, better built than I expected (all metal casing), quiet and and has the all important IR receiver on the front, which the Dell seems to lack. Havent loaded any BR software yet or attempted playback - will do so tonight. The HD sample video file that installed with Win 7 looked crisp and pleasing, but will tweak the tv settings (a Tosh 32" LCD) to see what can be improved.
I was smittem by the Zino's looks, but came to my senses. As an HTPC it seems a bit half-baked, leaving out the IR receiver and wi-fi is odd. As a standalone PC it does little than a similarly priced laptop could do. Dont know what Dell are trying to achieve with it really.
I havent read any consumer feedback on the Zino HD yet, so cant dismiss it completely. But on paper, compared to the ASRock, it doesnt offer the right price/performance/features blend. Also, more annoyingly, its waaay cheaper in the US than it is here. Rip-off Britain returns again.