While installing Adobe Photoshop CS5 Ext. Edition,Which option do i choose?

This is a pretty simple Question, Im currently running a Windows7-64Bit OS & Im currently trying to install Adobe Photoshop CS5 Extended Edition, Right now i am on the 4th part of the installation, on the side it is called options and on the top it says install options. On that part there are two options with boxes to put a check-mark, one is Adobe Photoshop CS5(64Bit) and the other is just Adobe Photoshop CS5 now it allows me to check both but My question is which do i choose or do i choose both? my guess is the 64bit version but i want to be sure before i continue.