Dells come with 64-bit or 32-bit Vista versions?

I'm considering buying a Dell E1705 . . . and even though it can be customized into a fairly good gaming laptop . . . I need to know whether Dell Laptops come with 64-bit or 32-bit versions of Windows Vista?

Feel free to also tell any other laptops which do or don't come with or without 64 and 32 bit Vista versions.