The location of the download to your computer is now controlled by whichever browser you are using since BI launch pad is web based. Therefore, depending on what your browser settings are, the report could be in different places.

GENERALLY, though this is obviously subject to change as browser versions change, Internet Explorer will ask you where you want to save the report and you can specify a folder.

Firefox generally places it in the Download folder, but you can change this by going to the main Firefox menu and selecting Options -> Options, and then look on the General tab.