mcenter mentioned LibreCad and after a casual look it seemed that it was not available for 10.04. after more looking it seems you can simply install it with a few commands from the terminal thanks to r00t4rd3d from the IRC.
For Ubuntu 10.04 use:
sudo add-apt-repository ppa:showard314/librecad
sudo apt-get update
sudo apt-get install librecad
Scott over at LibreCAD updated me on the repository for the bleeding edge.
That is an old version of librecad, 1.0 beta 5. But it will work. You
should be able to compile it from git to work on the older ubuntus.
For the record, the newest versions are in:
sudo add-apt-repository ppa:librecad-dev/librecad-daily
Cheers,
Scott
John