Guys, once again, thanks for the heads up with regards to the amount of data I could store. I guess the only options I have is to reduce the sample rate down, or, if 512 will store 3 and a half days, then 1024 would hold around a weeks worth....

I have one of these home weather station



http://www.foshk.com/Weather_Professional/WH1080.htm

Not sure what memory it has, but it sends temperature, wind speed, wind direction, rain fall, air pressure and humidity readings at least every 5 min and can store two weeks worth before roll over !

Does increasing the size of the memory have other problems when used with PICs?

If used on the same pins that the RTC (DS1307) is connected to what would be the ideal address to use, and do I use the IC2WRITE / IC2READ to send / retrieve data ?