You would need controller, drive and software.
The best way to upgrade your Amiga 2000 is a SCSI controller with ram option. A A2091 card can have 2 MB installed, or preferably a GVP HC8+ which can have 8 MB installed. Both cards will do.
Then it's just a matter of finding a SCSI harddrive and CD drive and install the software. Kickstart 2.0 or better is recommended, but you can do fine with Kickstart 1.3. Which software you choose depends on your Kickstart version.
