PC Specialist will offer more in respect of customer specifications. Dell go for the mass production line method, with limited upgrading available. Dell tend to be more corporate market, with a smaller section for individual purchase. Would mention that some 'Dell' products are re-badged, and it pays to bear this in mind, for future service advice.
If decide to purchase Dell,and there's no reason why you shouldn't, then look at their price discounting methods for home users. Free delivery, extra ram, bigger capacity hard-drives, different warranties and free printers, can make all the difference with good savings depending on the coding and media advertisement.