IDM is I suppose Internet Download Manager?
Hell I didn't use that crap since I switched from dial-up onto DSL.
And even back then I used Shareaza as it was open source, free and beside a few p2p networks it functioned as a resumable http downloader. Dunno if that software is still being updated though.
Anyway, while walking a thin line between legal and illegal stuff, you should always go for open source. In this case, try with: http://sourceforge.net/projects/freedownload/
Don't ask me if it's any good, I simply don't use such stuff. No need.