That ain't right at all.
The i7's memory controller can work with higher memory speeds than 1066Mhz. I have 1600Mhz RAM and it is running at its native speed of at least 1600Mhz. This involves adjusting the memory divider to set the RAM speed.
Dell, and some other PC manufactures, motherboards are locked and I don't think there will be an option in the Dell's BIOS to manually set the RAM speed. But thats down to Dell and not Intel.