I haven't tried it, but I wonder if this will work:

Download LimeWire for Linux. Copy your incomplete folder (downloads.dat or not) into your Linux Incomplete folder. When you open LimeWire, go to Library and click on Incomplete. If the files show up, resume them. Maybe it'll create a new downloads.dat that matches the files. I have no idea how it all works, but may be worth a try. Maybe even the downloads.dat file will copy too. I have a feeling it won't work because of the different platforms for the downloads.dat file, but hey... what the heck? If you're going to change platforms, you're most likely going to have to re-search for the files anyway. Might as well give it a whirl.

(p.s. I've had a few glasses of wine tonight, and I'm not very computer literate, so forgive the stupidity if that's what this is!! )