The V7 FAHClient installs a shortcut to "data directory" in AllPrograms. Inside of that directory, there's a subdirectory called logs containing a number of previous logs, renamed to be categorized by date.
Perhaps I'm missing something and I'm wrong in this instance but with the v7 client it is normal for the client to download a new WU before the old one is finished. Uploads and downloads are asynchronous so that there is always a WU running and there is no waiting time for a finished WU to upload and a new WU to download. I don't think you have a problem here other than finding out where the old log files are.
The old log files areaccessible from start->all programs->FAHClient->data directory->logs