I resume ftp downloads using konqueror all the time. If your download stalls out or is otherwise interrupted, just start the download over and you will be prompted to overwrite or resume the download.

I just did so today, in fact. I was downloading the 4 CD isos from MORPHIX, the 4 CD isos from Fedora Red Hat and the 4 CD isos from Slackware. Its just not my day! These downloads just kept on stalling, or my kids would boot-up the UnMentionable OS.

I kept resuming all day. I now have the complete download and the md5sums all check out fine!

HTH,
AJG