Regarding the issue with the audio driver. I found a slipstream walkthrough for a A200 PSAE3C model using nLite; I guess this is a similar European version,
Code:
http://www.tamalecart.com/toshibaA200/downgrade_Vista_to_XP.pdf
explaining the pain with the HD Audio, and as the author says "It must be the driver named hdaudbus.inf"
extracted from the hotfix kb888111xpsp2.exe, the hotfix itself woun't work.
You also need to slipstream the ICH8 HBM/AHCI SATA DRIVER.
Also remember it will only work on Win XP SP2.
All other drivers are apparently compatible (I wonder about the modem though?).
Anyway, to make it simple you can probably use i.e. Driver Genius Pro to "extract"/backup all drivers and burn the together with the Realtek HD Audio driver and the SATA Driver to a separate CD, used for system configuration after XP install.
So use the pre-installed Vista version to prepare your slipstream and to backup the drivers.
I have not yet tried this, but I will give it a go tonight, and hopefully it is as simple as it seems.
I tried AJR's suggestion with driverpack's slipstream, but I constantly had a BSOD, even with Mass Storage driver v7.12.1 and the even newer v8.1.15.
Hopefully this will do.
And it did! Everything is up and running, though I had to run driverpacks slipstream first and then pass this one through nlite, where I could
burn a bootable CD. This is the big issue I presume, you have to burn in a bootable mode, not just burn... (This mistake costed me hours of frustration and about 15 useless CD's)
The only issue I have left is the display driver, but I can live with it (I have some yellow! marking on these, not 100% compatible apparenty, but working. The system will not accept the driver from the Intel website and refers in the errormessage to the manufacturer, but I still have a resolution of 1024/768. I'll try some more tonight i'd really like the possibility of 1280/1024 stated.
Anyway, I just found some drivers on the German Toshiba site, once everything tested I'll post a link with all drivers needed - there was actually quite a few to update.