I agree that ISA cards should work. If it works with linux, especially Red Hat, then it should be possible with e-smith. The question is, though, is it worth it? If an arguably small investment in known supported PCI cards will solve the problem, can the time spent getting ISA cards to work be justified?
(mini lecture)
If you are in a commercial environment, either being paid to sell systems or being paid to administer them or being paid for other reasons but the sys admin job just happens to fall to you, then there is a value associated with your time. Is it worth many hours of research to make older and probably inferior hardware work, if a small investment in equipment will solve the problem? I once saw a group of engineers spend over 100 man-hours debugging a circuit, when it was known from the start that replacing a $50 circuit board would fix the unit. In the end, the engineers identified the chip that was failing, which turned out to be proprietary and cost more than the entire assembly, so the $50 circuit board was purchased anyway! A $50 problem solved at the cost of several thousand $$ of engineer man-hours. Not only was this money wasted, but 100 hours of other productivity was lost in the process.
On the other hand, if you are a hobbiest or home user and are spending time that might otherwise have been spent watching the television or surfing the web, then I reckon the time investment can be considered education. Such an education might have some value that could outweigh the actual time spent.
(/mini lecture)
imho