Gnucleus 1.6 Beta can't resume partial files that were downloaded just from a single host and have no extra file chunks. If you try to resume a "single-host downloaded" partial file you will get a lot of "remote canceled" in the extended info window. It happens even if you find more than 50 hosts with the same file you need to resume. I think this is a little bug. My system: Windows Me, 900 Mhz, 192 Mb ram and 56k modem.
Anyway, Gnucleus is absolutely the best gnutella client.