MarketXLS has an option in settings form which allows you to select where the data tables will be downloaded.

• Selection: This will make all downloaded data tables to be downloaded at one cell to the right and down of your active selection.
• Ask Me: This will ask you to select a cell where you want the data table to be placed
• New Sheet: This will create a new blank sheet and get the datatable placed on cell A1 of the new sheet