Idea: NFC support in PCs

Just had this idea while I was paying for something online with my credit card - how convenient would it be if I was able to just tap it to my computer or something and instantly pay for something like that. I can do it in most shops already, why must that be restricted? My Nexus S has NFC support (though I understand you can't use your cards with it either, the tech is there)

What do people think of this idea? I understand the security risks, but I think it would be incredibly convenient, say if it came default in laptop palmrests or the like.