You need:
1) The Software (
http://www.vbulletin.com) (or other MB software)
2) A Web Server (IIS, Apache or other appropirate web server.)
3) PHP and MySQL Running on that Webserver.
3) Knowledge of PHP, MySQL
4) Decent Internet Connection
5) General HTML Knowledge (or CSS,XML,DHTML,PERL whichever flavor you like.)
The server that I have running this website (and other websites) is:
Intel Xeon 3.20 GHz Dual Processor
4 GB ECC-RAM
RAID-5 Array with 6 32.4 GB ULTRA320 SCSI 15k RPM Drives (Hot swappable)
Dual Redundant Power Supplies
Dual Gigabit Network Connections, Running at 100MBPS
Windows Server 2003 Enterprise (IIS 6.0, ActivePerl, PHP & MySQL 4.xx.xx, MS SQL)
Mdaemon Email Server (from Alt-N)
This server *can* run about 300 websites, but only runs about 6 at the moment. I also have the Ultima and other databases mirrored to another facility in Chicago. My primary facilities are in Virginia.