I think the main reason is because I want to control outlets, lights, ect. And i'm not sure how to do that with a PC, but I do know how I would with an Arduino. I'm sure you are very right about the PC doing a better job than the Arduino, but I am using a PC program to do the speech recognition (BitVoicer) and then it returns a serial value. It is made for microcontrollers. If there is a better way of doing this i'd love to know.
It seems that you're already planning to do the voice recognition on the PC, and that seems by far the most sensible option. I don't know what form of output your voice recognition software provides, but I'm sure you could find freeware to output in pretty much any way you want.
For the actions that involve interacting with hardware, it would be sensible to implement those on an Arduino and have them triggered and controlled by an application on the PC. For actions that involve interacting with things on the PC (such as opening browsers) there would be no need to involve the Arduino at all.
Basically, it seems to me that you will need an application on the PC that receives commands from your voice recognition software and either executes a command on the PC or sends a command over the Arduino's serial port to switch hardware on and off.
There is a huge variety of options for ways to implement the PC side. You could do it in Processing, or write an application in 'C', C++, C#, Java, VB or whatever other language takes your fancy. It's possible you could even find voice recognition software which includes the capability to launch local utilities and write to a serial port, in which case you may not need to write anything at all on the PC.