So ive got 4 400gb ATA/IDE (I believe they're the same?) hard drives, and I want to put them into a raid configuration with a raid card.
It wouldn't be worth it for 400GB SATA drives. ATA/IDE is even worse. If you can dig up an old PC with those ports (two master/slave ports), you can load it with some "NAS on a disc" software (don't use a ZFS based NAS with less than a 8GB PC).
If you can dig up 4 sufficiently cheap IDE to USB connectors, you could even build a NAS on a Raspberry PI device (or similar). Don't expect great performance, but you can't expect much with HDDs, especially with IDE connectors.
So it all depends on what your use case and goals are. If you're just trying to find a practical use for some aged hardware, sometimes that use is a paperweight or doorstop.