try speed download. you can set the download queue to start everyday and add files to download from a url, it probably will fit what you want to do.
EDIT: Automator might be an easier option because you can just save the workflow as an application and keep it on your desktop and when you want to download the file you can just start the application.
Well, I figured if he was asking if this was possible, then Automator would be a better option than cron job. That's like answering a guy who asks if it's possible to retread his tires by saying yes and pointing him towards a rubber tree with a knife and a mallet.
Ha, thanks guys. I haven't used Automator as yet, so I'll see what it can do. Otherwise, I'll investigate curl and wget... believe it or not, despite the n00b style question, I do have a bit of scripting experience