It probably got in through the heat vent (or perhaps the optical drive), so "blowing it out" probably isn't in an option, because the fly likely blindly navigated his way around until he found his way to the LCD screen, and then died to death due to extreme heat.
Your only option is probably to disassemble the computer, unless you can lift up and shake the computer until the little guy falls out somewhere, but I wouldn't recommend doing that.
This certainly is a difficult (and hilarious) situation. The fly is probably gonna start to stink, soon. Especially if you keep using your computer, because it's extremely warm inside the computer.