Best/easiest way for global sensor data storage?

Hello,

I am only a few months into the Arduino world and I am loving it. With not much programming skills I was able to get my Uno posting several sensor's data to Xively for graphing purposes. I would like to add more arduino's and sensors throughout my house. I recently purchase a bunch of NRF24L01+ and played around with them. I was able to transmit data from one Uno and see it on the other.

I don't want to keep buying ethernet adapters and programming them to publish their data on Xively. The ethernet adapter aren't as cheap as the NRF's and I would like more graphing options other than what Xively can do for me.

I recently bought a Raspberry Pi B+ but haven't played much with it.

SO.....my main question for you guys:

With not a whole lot of programming skills except for what I did above, I would like to harmonize my sensor data to one location usuing the NRF's (this seems the cheapest way). I have seen a TON of ways to do this, but just don't know the best way for me to start. I bought the Pi with the intention of usuing that as my master radio/data collection. But then I seen someone usuing a computer running windows with a thingspeak server. Then a few guys I seen sending all data to one Arduino with a DATA logging shield.

With there being so many different way's to do it, I need some advice on where to start. Remember, my main goal is to take my sensor data (pressure transmitters, range sensors, flow meters, temperature and humidity) and be able to graph and store the data for years to come. I would like to be able to overlay some of the graphs according to time/day/month/year.