In retesting stuff, I did discover that the new 8GB stick does in fact work with Vector. The other 8 GB stick I still can't get to work, however. It does work in Windows (XP), but not in Vector. I reformatted it as FAT 32, and tried it, but it still doesn't work in Vector. Mystery.
I'm going to chalk it down as a faulty stick. So, this thread is solved.