Two most common ways of remotely connecting to your PC is through Remote Desktop Connection (Windows only), or using VNC server / client software.
There are several iPhone apps that will allow you to do this, and after doing testing we have narrowed down the choice to one of each – and they are both developed by the same company, MochaSoft.
RDP Lite – this allows you to connect to a Windows based PC that has remote desktop enabled. Click here for the product web page
VNC Lite – this allows you to connect to any computer that is running VNC server on it (Windows, Mac, Linux). Click here for the product web page
You can download RealVNC server from here.