I'm currently trialing Returnil and I like it a lot. It seems to do its job well and unobtrusively. One downside to the free version is the restricted capability to turn off session lock without a reboot. For this reason I'm wondering about purchasing the full version. Before I do (and this goes against my initial desire to maintain a zero-cost security solution) I was wondering if there were any other programs that do a similar job as well.