The Downloads you ah.. "download" are just setup files or whatever for the programs. Unless you want to keep the files to re-install them later on, you can delete them. It's like holding on to a box for a TV. If you toss out the box, the TV will work just fine, and you save on space. But if you want to use the box later for packing, shipping, warranty, you need to get a new box. So if you delete the files from Downloads, and you want to re-install the program, you need to download it again.