One card should be no problem, although that link was written by a fairly paranoid person in my opinion.
If you make two payments on a transaction, and there is problem down the line, only the first payment will be refunded by PP or by eBay. The second payment is up to the seller.
I'd suggest depositing the card money to your credit card and using that to pay for your purchase.
That way you have three levels of Buyer Protection.
EBay for 30 days from delivery.
Paypal for 180 days from payment.
And whatever the chargeback policy of your credit card is.
