If you would like to play your electric guitar through your PC speakers, you can as long as you have the appropriate adapter. Standard electric guitars and amps use cords with quarter-inch jacks, whereas PC speakers use cords with eighth-inch jacks. You will need to obtain one of two types of jack adapters to play your guitar through your PC speakers: if your PC speakers can plug directly into an electrical outlet, you will need an eighth-inch to quarter-inch jack adapter; if your speakers need to be plugged into your computer to get power, you will need a quarter-inch to eighth-inch jack adapter. These adapters can be obtained at most electronics stores and some music stores. Also, you can find several options to purchase through the link in the Resources.
For PC Speakers with their own Power Supply
Apply the eighth-inch to quarter-inch jack adapter to the male end of the cord that would normally run from your PC speakers to the back of your computer.
Plug the adapted quarter-inch end of the PC speaker cord into your guitar.
Plug your PC speakers into a wall outlet, turn them on and begin playing your guitar.
For PC Speakers without Their Own Power Supply
Turn on your computer with your PC speakers plugged in as you normally would.
Plug one end of your guitar cord into your electric guitar and apply the quarter-inch to eighth-inch adapter to the other end of the cord.
Plug the adapted end of the guitar cord into the eighth-inch jack labeled with a microphone symbol that you will find on the back of your computer near where your speakers are plugged in.
Open your computer's Start menu, then click "All Programs --> Accessories --> Sound Recorder".
Begin recording a sound with the Sound Recorder program and play your guitar. You should hear what you play coming through your PC speakers.
Things You'll Need
Jack adapter, eighth-inch to quarter-inch OR
Jack adapter, quarter-inch to eighth-inch