I recorded a video showing Ubuntu 9.04 Netbook Remix (UNR) booting on a Acer Aspire One (512MB RAM, 8GB SSD) on Monday. This time I recorded Windows 7 Beta booting on an Asus Eee PC 1000HA (1GB RAM, 160GB HD). Both netbooks use the Intel Atom N270 processor.
Windows 7 Beta took 34.97 seconds to boot to the Windows 7 login screen. UNR took about 36 seconds to boot on the Acer. Windows 7 takes another 20 to 40 seconds (depending on how you count) to get to a useful state after Windows 7 starts up various extra but necessary processes like anti-spyware and anti-virus apps as well as a bunch of background application update checkers.
So, in general, both UNR and Windows 7 Beta took about a minute to get from a cold start to a useful graphical interface state.