An easy test is to sign a message using your private key and then verify the message using your public key (your receive address). This can be done using Bitcoin-Qt by selecting File->Sign Message.

1. Sign a message by entering your receive address and some message text (anything you want). Select Sign Message. Copy the signature to the clipboard
2. Verify the message by entering your receive address and the message text (exactly as you entered it for signing). Then paste the copied signature into the signature field. Select Verify Message.
3. If everything is working correctly, you should get a message verified status.

The receive address is based on the private key used to sign it's transactions. If you can see it at all, it means the private key must exist. Further, the address contains a hash so you can't make a typo using it. You can be perfectly confident that it works.