ok, so it is basically a 'wallet address' and is basically useless with out the key?
Correct.
Check your harddrive for any files called "wallet.dat".
Most of the time there will be a folder in your drive at C:\Users\(your pc username)\AppData\Roaming\Bitcoin
Check if you have a folder like that.
Do you remember what miner you had running? Do you remember if you had Bitcoin core running?