Hello!
Another alternative for Mac OSX users are also Direct Connect most famous for the fact that it is the best network to get movies and extremely large files downloaded. You can get it here:
http://www.neo-modus.com
However I dont think that you should give up on LimeWire and Gnutella just yeat.
The Could Not Download Awaiting Sources message is not really a big problem. In previous versions of LW you would just get into Requery Sent status when a connection to a host you where downloading from got dropped. In 2.9X versions Requeries are no longer sent and you will get the new message instead. The solution to it is to first highlight the file and click the Kill Download button. This will temporarily delete the file from the download list but dont worrie it will come back just look after the file in the search result list and double click it again and once again the same file will appear in the download area and a new connection attempt will be made. If unsuccessfull you have to search for new sources for the file just use the exact seame search term as the filename and if the file is found from another source LW will attempt to connect to them instead and get it from there instead. If succesfull the file will get downloaded. You might sometimes have to perform the above described procedure multiple times during a download specially for large files but eventually you will get the file. Downloads on Gnutella simply have to get babysitted and attended!.