Do I need 64 bit Windows 7?

Episode 993 (2:05:18)

Steve from Ohio

Steve bought a new laptop with 32 bit Windows 7, but he can't see all of his RAM. Leo says that's because 32 bit will only see 4GB of RAM, so if he has more than that, he'll need to go with 64 bit Windows 7. Can he install it over the 32 bit? Leo says it's better to format the hard drive and start over. The chatroom says that he doesn't need to buy another copy, just download it from Microsoft and use the same License key.