Well a USB ideally. I can get an SD card if needed.
You need to.
So shielding with an SD card will basically give me more space to store data?
Yes a shield with an SD card reader/writer will give you space to store more data - a lot more data.
Does the arduino board have a slot for the card?
Did you see one on your Arduino?
Also, is the arduino software compatible with newer OS's? like windows 7 or vista??
Yes.