First of all the ADAT Edit card sucks the wanker. Just ask Ed (sonusman)...only works in Windows95 and doesn't work that well.
As far as putting a machine together....you *might* be able to use the monitor, keyboard, case, & mouse....but then you might not.
Don't bother working with an AT style case. You'll need a new one. When you go ATX you'll need a new keyboard and mouse (assuming they weren't PS/2 to begin with). And that leaves the monitor which should still work depending on its age.
I guess it really depends on what you're getting. Let us know.
Slackmaster 2000