Synology's product line-up is pretty broad. At the top you have products like the DS713+, a powerful NAS with space for two disks. It's also very expensive. The DS213j is a much more affordable option, and you still get all of the features of the impressive Disk Station Manager firmware and room for two hard drives. It's a great way of getting introduced to a Synology NAS.
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips