The pictures look fine to me. With SSDs, hours really don't matter - the big issue is how much they are written. The 40GB 320 was specced for a lifetime 60TBW - so you've exhausted about 3.75% of the life of that drive.
I'm running a pair of 320s for my boot devices (mirrored). The oldest of the two is at about 16TB written - still running just fine. In short, go for it, and back up your configuration file just in case (you should be doing this anyway, regardless of the boot device). Ensure SMART monitoring is configured (again, you should do this anyway). If you're sufficiently paranoid (as I am) and have the ports and space, add a second boot drive and mirror them.