I have used simulated Vista Icons and IcoFX 1.6, by combining icons and using effects. Formats:
256x256 32b
128x128 32b
96x96 32b
64x64 32b
48x48 32b
32x32 32b
24x24 32b
16x16 32b
48x48 256
32x32 256
24x24 256
16x16 256
48x48 16
32x32 16
24x24 16
16x16 16
The possibly problem is for 16 colors users (Win9X) that the icons look somehow flicked in 16 colors.