Not from User Info table  but from the user profile:
Following sample in a console app should help:

ServerContext oContext = ServerContext.Default;
UserProfileManager upManager = new UserProfileManager(oContext);

foreach (UserProfile cUser in upManager)
{
Console.WriteLine(cUser["PictureUrl"].Value);
}
Console.ReadLine();


Now the above is for MOSS where we have global profiles but if you are looking at WSS then the profiles are site collection scoped and stored in user information list that is hidden and you can loop thru it programmatically as explained in this blog:
vspug.com/.../