When I click the "Receive coins" tab, the receiving address is in the list of my Wallet.
In the bottom left of my Overview screen I get a green V sign, and it says "Up to date" and "Processed 224578 blocks"
Sounds right.
I created my wallet.dat on a Linux system with the Linux bitcoin client,
moved it on a USB stick to a Windows machine, where I'm running the Windows bitcoin client.
Could this be causing troubles?
Nope, that wouldn't cause any problems.
To be honest, I'm not entirely sure what happened, but the important thing to note is that according to the blockchain that address now has 0.03BTC (which you can see here
http://blockchain.info/address/14BjCuxbgPH2gnnyKqMS7f7JXpgmFzLUEy ), so your BTC is safe, its there, but for some reason your wallet software isn't recognizing that it is.
Maybe to a rescan?
From command line do: bitcoin.exe -rescan