Whoa... a dial-up connection?
May I ask what download speeds you get with your connection?
Not trying to burst your bubble, but JDownloader's "resuming download" only works to a certain extent. Especially if you're a non-premium member, sites like Bitshare will limit your download heavily--if you make frequent "pauses" between downloads, the site will simply restrict your IP from downloads for the entire day.
I'm not sure what you're talking about by "Not all games have torrents". If you search Google with the following format: "[ReleaseDate][Producer](Title)", you should find at least 5 different torrents. Now the problem with those torrents being dead or alive is a different story.
DDL, I've found, is rather inefficient because it restricts download speed, you cannot resume downloads for some hosts (fortunately, JDownloader, as you did see, has resuming downloads for some hosts), and restricts transfers daily.
Although I would recommend playing around JD just so you can get the feel of it, I wouldn't suggest using it daily unless your ISP specifically restricts P2P (like my crappy school internet). There's a reason why P2P is such a popular method for filesharing--you should be happy that you have that option.