Basse,
Have you ever tried GoZilla(Download Manager)? It'll let you adjust how many downloads you can have going at the same time. What I really like about it, is that it will save download information and then allow you to download later, as many things as you like, while your doing something else(while your sleeping). It also supports broken downloads. If you get cut off it will resume where it left off, which is very nice when downloading large files. It also will check different sites for the same file and find the fastest download. And if there is a slowdown or problem at one site it will automatically switch to a different site.
I use it while I'm surfing and if I find something I want to download I click it, Gozilla opens, checks other sites for the same file, lists them from fastest to slowest. You then either click download now or download later. You can add as many downloads as you like and then you can Either manually start the download or set it to run at a certain time. Under options is where you set the number of downloads that you allow at one time. I usually keep it at two but have dowloaded as many as four at one time.
GoZilla is freeware/shareware. Free version has ads, but they don't bother me. There is also another program called GetRight that does the same thing.
GoZilla