Yes and no.
You can set up ypur PC as a web server fairly easily using Windows IIS click here or Apache click here but many ISPs do not allow you to host your own website and the security implications of using your PC as a web host are pretty horrific.
You also have DNS resolution issues to consider and a third party product or service like NoIP click here would have to be used to point your site visitors to your site unless you have a static IP address.
Frankly, for what you get in return for the cost of hosting, it simply is not worth the hassle or risks involved and if your site is anything other than just a slight hobby to you, running your own web host is completely impractical for a reliable service.
Just let a web host do what they do best and use your computer as a PC.