Which 32 bit kernel runs better under AMD64 architure, 686 or k7?

[Marcello Di Marino Azevedo <marcello_dimarino@superig.com.br>]

Probably you are tired to see tons of questions like this, but...

I have two new servers coming for a critical mission application. My
question is simple, will sarge i386 port (32 bit only) runs fine under
an AMD64 X2?

For example, if I install kernel 2.6.8-k7-smp it will see 2 CPUs?

Which 32 bit kernel runs better under AMD64 architure, 686 or k7?

Thanks,
Marcello.