I have been experimenting with Windows 7 for a few months now on various machines. It runs very well on a Sony Vaio TZ with a 1.2 GHz core2 duo processor and 2Gb of memory, and that's with reasonably demanding use. Assuming an implicit dual core requirement in this, I would therefore say that Microsoft's 1GHz minimum processor spec is probably reasonable. While I haven't tried whipping memory out of the Sony, I did load Windows 7 onto another machine (an old Philips notebook) that had a faster processor but only 1Gb of memory. That did not run very smoothly until I put more memory into it. I would therefore suggests that 2Gb RAM is probably the safest working minimum for most situations.