We recently bought a batch of new Dell XPS Studio workstations that have a 2.66GHz Core i7 920 CPU, 6GB of RAM, a 750GB 7200rpm drive, and an ATI Radeon HD 4850 video card. I took my machine, and put a 10,000rpm 300GB Western Digital VelociRaptor drive in it, and installed Windows 7 Beta1 (just for testing purposes).
The Core i7 has four physical cores, with hyper-threading for each core. This means that Windows sees eight cores. These CPUs have an integrated memory controller (so no front-side bus), and 8MB of shared L3 cache.
Windows 7 on this machine is blindingly fast. I have installed Visual Studio 2008, SQL Server 2008, and Office 2007 with no issues. The CPU-Z, WEI, and Task Manager screenshots are shown below.