System bus and front side bus don't have to be directly related...sure it's ridiculous that Intel dishes out 533mhz and 800mhz so people think "well that's higher than 266mhz" ... but it all depends on the CPU's architecture
Higher system bus is more powerfull than having a higher fsb.
For instance
One 200mhz system bus/FSB is better than
100mhz double pumped FSB to 200mhz system bus.
Basically higher the "TRUE-single pumped" fsb the bigger the real gains. Intel also needs the 800mhz to keep that HUGE 20 stage pipe full compaired to XP's 10. So twice IS needed!
I'm pretty skeptical about those temps... I've never seen CPU temps LOWER than the motherboard temps using standard air cooling. Not even on a non-overclocked CPU.