Bamboo HQ Wallpapers
Size 1920×1200
Recent and awesome:
The wallpapers included in the last build 7057of Windows 7, which is supposedly the first release candidate of Windows 7. Looks like they really made an effort and Windows 7 has some awesomely awesome wallpapers.
Nature
Windows 7 HQ Wallpapers
Part 1
Part 2
Part 3
Part 4
Part 5
Previous builds Windows 7 Wallpapers:
Windows 7 Wallpapers (build 7000)
Windows 7 Wallpapers (international build 7000)
Fan Art Windows 7 Wallpapers