Try to get 480x320 at least. Most Android developers, like myself, will target this resolution first. This is the baseline resolution that Google considers Normal. Although many applications should work on smaller resolutions/screens without problems thanks to Android's layout managers, some games and graphics-oriented applications will not.

If you have the time and don't mind a little technical reading, take a look at this Android development article - Supporting Multiple Screens. Android developers design applications based on this document.

This post has been edited by Andrew Lim: Sep 6 2010, 06:49 PM