From rage3d.com:
<< Radeon 8500 OEM: 250Mhz Core, 250Mhz Memory, Does not incude games or dvi to vga adaptor
Radeon 8500 Retail: 275Mhz Core, 275Mhz Memory, Includes games on a seperate game CD, includes other cables etc.
I know an ATi representative had said that at the time of his writing that OEM's would be 275Mhz, but that decision was obviously changed for whatever reason.
The cards shipping from Dell are retail boxes. >>