I know I've seen this mentioned several times in several threads here in the Vista forums but I just can't seem to get these two unknown Devices to register on my Mini 9. I installed a VLited Vista Home Basic and with a few cycles of the Updater everything has a driver except these two mystery items.
I installed the "Smart Battery" or whatever it was called as well as the Dell JMicron drivers, Intel Chipset drivers and a smattering of other things off of dell's support site (like the trackpad driver). So far everything is working pretty good but those two "Base System Devices" still remain in the Device Manager.
Also possibly related to this, my "Windows Experience Index" rating is still a 1.0... the thing has a little notice saying "new hardware detected" and it wants me to update the score but every time I do it either goes through it's iterations and nothing changes or it hangs up on the last leg and just sits there and has to be canceled.
Outside of these niggling problems Vista runs very well on my mini that has a 2gb crucial memory chip and a 32gb runcore
ssd. I disabled indexing, removed the page file and did all the other tweaks I saw people talking about here and the speed and responsiveness is very good.
Edit: over the weekend I blanked my mini and reinstalled Vista and all the dell drivers. Magically the two "Base System Devices" are gone now so I must have missed a step earlier somehow or perhaps a driver "didn't take" properly.