How often is the data transmitted / updated to the base unit? i.e windspeed and rainfall? The reason I ask this is that on the product description on a few sites, it says that data is recorded every 5 minutes, upto every 24 hours?
It's user configurable between 5 minutes and 24 hours. I have mine setup to record data to the internal memory every hour, as I'm really only interested in statistics on an hourly basis. But the data displayed on the base station is real-time, and isn't affected by this aquisition cycle setting. Each sensor has a cycle time, so the wind sensor sends data to the basestation every 33seconds for example.
Is there anyway of having the data instantly update onto the PC or is the computer mainly for reviewing the previous collected data?
Yes, if you leave the basestation connected to the PC (via USB), it constantly displays the current data on the PC as well.
I used to have mine connected to the PC all the time, but now prefer to have the base station out in the hall where I can see it easily, and once a week I connect up to my PC to download the data. I then analyse the data using Excel to show monthly rainfall average, max/min temperature, maximum wind gust, etc.