Can you use any motherboard in any case?

NO!

Gee, wish it was that simple. No, there are way too many things to list here as to why one is different from another, the year, month, day, hour,- type, hardware and software to go with it, the list goes on, and on.

In general, if you buy both a case and a motherboard today, they will be compatible. You mostly run into problems when trying to put a new mb in an old case. The old cases had "AT" power supplies(2 connectors), and new cases and mb's use ATX power supplies(a single 20-pin connector). In some cases, you can run into problems with cases and mb's that are both ATX, if the power supply output is too low (< 300 watts). You can get a new case on eBay (with a decent power supply) for 30 bucks or so.