DAW-Sequencer for free: Tracktion 4
Tracktion 4 has been released as a freeware-version. The DAW-sequencer with the one-window-concept, allows you to skip through different tabs and is easy to manage, especially for beginners. It includes eight effects, some instruments (like a sample-player) and supports the Linux- and Mac-systems (also for 64 Bit).
If you want to use Tracktion 4 as a full version permanently, you need to activate the DAW before using.