I've been playing around with both the 32 and 64 Bit versions of Vista
Ultimate on my new PC. The system specs are as follows;

CPU: Intel Q6600 (Quad Core 2.4)
MB: Intel DG965WH
RAM: 4Gb (1Gb Transcend PC 800MHz x 4)
Video: PNY 8800GTS

In Vista 32-Bit, System runs well (Good CPU Utilization) but will not see
all 4Gb RAM (3.2+GB Seen), system seems to be using a fair amount of RAM.
Windows Experience score Rates the CPU at 5.9

In Vista 64-Bit Systetm runs significantly slower than the 32-Bit version.
CPU Utilization near 50% with system at idle for all four cores. Running
simple software pegs all four cores at 100%. System sees all four Gb and RAM
utilization is better than in the 32-Bit. Windows Experience Score has
dropped the CPU to 4.6.

Two other IT people at work with similar system specs have the same problem
in 64-Bit Vista.

Anyone getting good results running 64-Bit Vista on an Intel Quad-core?

ajf