Premiere does support SMP (ver 5.x, 6.x). Many/most/all of the CODEC plug-ins do not. Plan on rendering on one processor only.
Premiere also like lots of memory. When it starts, it'll capture half of the available RAM.
I like Premiere, but I've been trying Vegas Video lately, and I'll probably switch to VV for most of the common stuff.
FWIW
Scott