Hi karlo54 - Welcome to w7forums
Having a choice initially to select 32-bit or 64-bit when you first power on the computer would depend on the manufacturer and whether or not they included the choice. In general you will not have this choice. However, your worries could all be for nothing. Most 32-bit applications will work fine on Windows 64-bit version.
The average home user will never find an application that will not work. With that said, you may have to do a little tweaking to get some of the apps to work such as XP or Vista compatibility modes. The main concern for all users of Windows 64-bit is whether their hardware has 64-bit drivers, such as printers scanners and cameras.