Another option might be this :
I had the same problem...
Try to use NLite
With this free tool you can create a custom XP installation disk (ofcourse you need a working pc to run this tool....).
It images your xp-cd and you have the option to add drivers. the drivers you need to add for the xp installation to work are in the "Intel Matrix Storage Manager-7.5.0.1017" zip
link
I used the drivers in the ICH8M_32bit directory.
also from the above mentioned site ...
Good luck
If I were you I would go over that Toshiba site with a fine tooth comb seems then answer might be over there ..