There are several ways to do this as mentioned above.
You can even use MyHouse although that is very slow and your relying on the X10 server which isn't 100% reliable.
I've used RealVNC (free version) similar to how
steven r set up his system from day 1 before any of the plug-ins were available.
My system and some others will allow the PC to boot without keyboard,monitor or mouse attached (check your BIOs setting to enable\disable this, and set AHP to start up on boot up!
Since then I've used a number of third party software to access my home automation system even X10dispatcher has its own server built in and works great on a home network!