you'll require following to set up a web server:
1: a PC, doesnt have to be fast, a P-2 266 with 128MB ram will be ok to host 4-8 web sites with normal traffic. but hard drives have to be really good ones, S-ATA or SCSI.
2: Static IP (can be bought from any internet service provider)
3: a web server software over your operating system, normally Windows comes with web server built in, WIn98/Me have PWS (small, not recommended), 2000 and XP Professional comes with IIS Builtin. thats a pretty strong web server,
else than that, you can even download and install the Apache server, that is free and is most popular at the moment, as it can work platform independently. can be downlaoded from
www.apache.org
and here you are, ready to deploy your web host.
*, a piece of advice, dont host porn sites
, or i'll be the first to hack and shut down your pc