I know that USB devices take power from the 5V rail only to a max of about 8W otherwise they have their own power supply, however i have no idea about pci cards. possibly similar, have a look on the manfacturers site, they may have some power specs.
As for the alternative to ITPS whilst still using pw-70a i am not really sure, i thought about the possibility of using a regulator similar to that of the lilliput 'egg', but i'm sure someone will step in and tell us that it cant deal with anything like the power required (100W-ish). Anyone?
As i see it you have 2 choices, either spend extra money on laptop components, or spend it on an opus.