If you installed using the Synaptic package manager on Lucid Lynx or Karmic, then I can tell where the real files are: /var/lib/boinc-client

chown is the command to change ownerships. Can't remember exactly, but I may have done that from a root terminal window and then left it on my user account with reading rights for the boinc account and everyone else.

The line to add to the <options> section is <no_gpus>1</no_gpus>. The line may already be in there. Opposed to the windows installer, the Linux Synaptic install creates a fully populated cc_config.xml.

WCG has an automatic GPU work backoff in place of 7 14 days, for WCG. If you hit the update button that is though overridden i.e. GPU work is checked, then it's back to 7 14 days wait.

edit: Did it with help from this bookmarked webpage: http://www.tuxfiles.org/linuxhelp/fileowner.html and ran sudo chown username cc_config.xml.

edit: updated the GPU backoff time!

Superb, then please edit your opening post and insert [RESOLVED] in the title as per my post. Others will then know a fix is close by.

happy crunching, at WCG, where else :D