Thanks for all your help guys. I've made the decision to go with an RPI, connected via serial to the arduino, which is still acting as the NFC reader. I did this because I really think I do need a relational database, because there isquite a bit of different data I need to store with the tags, and I still can't figure out how to write to them.
Ill also need to do commands like, has this tag been scanned today, if so, yada yada, and so I think a relational database would be easier and faster for that. Thanks for your help anyway guys:)