There is no such thing as a validated DDR 533Mhz module yet. Even the 400Mhz models aren't true 400Mhz, but 166Mhz models overclocked. JEDEC hasn't approved the 400Mhz DDR for mainstream use yet until the technology develops further, which may not exist till DDR-II even. The fact remains, RDR Pc-1066 offers the best performance.
I was always trying to compare DDR and RDRAM @same bandwidth.
that is like trying to compare the Athlon and the Pentium 4, both using Pc-266 DDR. Then, the Athlon would be much more competative, but the Pentium 4 wouldn't have it's full potential tapped.
"When there's a will, there's a way."