Apt must have done something to update my kernel from 2.6.24 to 2.6.26. The 2.6.24 kernel was default from the Lenny install CD that I used. I can only mount the /boot partition (obviously) because the rest of the drive is encrypted (laptop security ftl). Of course when I try to set GRUB to boot into 2.6.26, it stdouts some errors about modules and the root filesystem. What do I do about this? How do I mount a LUKS filesystem to get the data off there (while I screw around with the box)?

This is pretty annoying given that my battery just died. It doesn't hold a charge for more than about 8 minutes. By the way, does anyone know where to order T40 batteries? Lenovo doesn't have them in stock because the model is quite old (but good for my purposes).

If you post those errors and what modules it complains about, it would make it easier for LQ people to help you figure it out.
If you go back to the 2.6.24 kernel and initrd then you should be able to boot up as before, unless something else was changed.