A Windows Vista Capable PC includes at least:
A modern processor (at least 800MHz).
512 MB of system memory.
A graphics processor that is DirectX 9 capable.
Windows Vista Premium Ready PCs
To get an even better Windows Vista experience, including the Windows Aero user experience, ask for a Capable PC that is designated Premium Ready, or choose a PC that meets or exceeds the Premium Ready requirements described below. Features available in specific premium editions of Windows Vista, such as the ability to watch and record live TV, may require additional hardware.
A Windows Vista Premium Ready PC includes at least:
1 GHz 32-bit (x86) or 64-bit (x64) processor.
1 GB of system memory.
A graphics processor that runs Windows Aero.
128 MB of graphics memory.
40 GB of hard drive capacity with 15 GB free space.
Audio output capability.
Internet access capability.
Windows Vista Capable and Premium Ready footnotes
Windows Aero requires:
DirectX 9 class graphics processor that:
Supports a WDDM Driver.
Supports Pixel Shader 2.0 in hardware.
Supports 32 bits per pixel.
Adequate graphics memory.
64 MB of graphics memory to support a single monitor less than 1,310,720 pixels
128 MB of graphics memory to support a single monitor at resolutions from 1,310,720 to 2,304,000 pixels
256 MB of graphics memory to support a single monitor at resolutions higher than 2,304,000 pixels
Meets graphics memory bandwidth requirements, as assessed by Windows Vista Upgrade Advisor running on Windows XP
What this means is that the new 13" MacBook should be fully supported as a Windows Vista Premium Ready PC... errr... Mac, as long as 1 GB or more RAM is installed. The MacBook's integrated Intel GMA 950 graphics has the required features for Aero Glass, which includes things such as translucent windows elements. Proving this is this video which demonstrates a beta version of Windows Vista running with full Aero Glass functionality on Intel GMA 950.