Multiple sizes... I would draw the icon at the largest size you can, and scale it down to the smaller sizes for best visual effect.
IcoFX allows you to add multiple icon sizes into a single .ico file, so you can get the best looking icon depending on the users system.
This might be a good read:
http://msdn2.microsoft.com/en-us/library/aa511280.aspx
It's aimed at Vista, but most of it still applies to XP as well. It's the designer guidelines for icons for windows applications.
According to it, the icon requirements for a control panel or application icon are the following: Application icons and Control Panel items:
Anyway, that page contains a lot of other useful information, including what angle and perspective to use in 3D icons, what kind of drop shadow settings to use, etc.
And other design guidelines such as not using shadows in icons at 24x24 or smaller, or recommending the 3D look for icons, except for the smallest sizes which need to be a head-on 2D view again.
IcoFX allows you to add multiple icon sizes into a single .ico file, so you can get the best looking icon depending on the users system.
This might be a good read:
http://msdn2.microsoft.com/en-us/library/aa511280.aspx
It's aimed at Vista, but most of it still applies to XP as well. It's the designer guidelines for icons for windows applications.
According to it, the icon requirements for a control panel or application icon are the following: Application icons and Control Panel items:
The full set includes 16x16, 32x32, 48x48, and 256x256 (code scales between 32 and 256). The .ico file format is required. For Classic Mode, the full set is 16x16, 24x24, 32x32, 48x48 and 64x64.
Anyway, that page contains a lot of other useful information, including what angle and perspective to use in 3D icons, what kind of drop shadow settings to use, etc.
And other design guidelines such as not using shadows in icons at 24x24 or smaller, or recommending the 3D look for icons, except for the smallest sizes which need to be a head-on 2D view again.