I want to be able to pay PC Minecraft WITHOUT lag, Is this a computer that will give me that?

Your question would be more effective if you had bothered to list the specs/model of the computer you're asking about.

This question is hilarious

I would recommend running this, it'll give you a rough guess of how your performance will be reflected.

http://www.systemrequirementslab.com/cyri

BUILD a pc?