I've done some more tests with the Vaio PCG-FX601 using a copy of Knoppix that runs straight off the CD drive, and it runs as well as it looks. The keyboard seems perfect, the trackpad and mouse buttons work fine, the DVD drive runs fine in CD mode at least, and the battery gets to about 80% charge before the indicator light stops flashing. However, and this intrigues me, Knoppix indicates that it is still charging past that point (it's at 86.60% as I write this), but the rate of charge rapidly drops to about half of what it was normally, and then drops down a bit more slowly (at this point, it's 2040 mW, but still dropping). My guess is that it'll get to around 88-89% before it stops charging any further. Pretty impressive for a £4 untested system from the early 2000s, at any rate! I shall try this test with the Toshiba, and indeed the other laptops in the near future.
EDIT: Well, colour me shocked. It actually indicates that it has now reached 100% battery. Wow.