Every transaction is registered in the block chain. You have a wallet, holding pairs of public/private keys. You give your public to people that pay you, they sign their coins to your public key. You then need the matching private key to use the BTC so:

- Your keys are in your wallet, means lose the wallet, lose the BTC. Someone gets your wallet, they can send themselves the BTC.
- Everything else is in the block chain, means you can access your coins wherever you want as long as got your wallet with you. Careful with that though.
- Public addresses are only to send BTC to you. Someone can use it, and you'd be getting free BTC =P
- Right now you are expected to provide security for your wallet on your own. Client based wallet encryption is under dev/testing right now.

C:\Users\"Lightspeed"\AppData\Roaming\Bitcoin\wallet.dat

is this my wallet? the file I guard with my life so to speak? lol

thank you for your help, it makes much more sense now

so is it just a matter of making offline backups of that wallet?
or could I have 2 wallets, one I use online during mining and when I get coins, transfer them to a wallet that is kept on a HDD not connected to the internet?

I make an encrypted version of that file that I store in the cloud, USB stick and so on-
You can definetly send your coins to an offline address. I would test it now and then to be sure and feel comfortable with importing a wallet.