I've brought something off Ebay which i paid for straight away via paypal.... the sellar then contacted me and said that she did want payment via a cheque as she can't use paypal and doesn't know how to get her money out.

Why have it as an option i hear you cry.
I sent a message back saying sorry didn't see that in the listing but i can't get my money back from paypal unless you reject it or 30 days expire with it being unclaimed.
Today the item has arrived...... with the money still being unclaimed. So i currently have both the money (sat in ebay unclaimed which if stays like that will bounce back in 25 days to my card) and the item.
I would think Win Win but i don't know what might happen now and i'm a bit worried!