Are you needing read back the output of the external process? If not, the I would use system as cdarke has suggested.

However, if you do need to read back the output, then you might consider using back ticks. Just beware that using back ticks can create problems if you're not careful. (For more details about using back ticks and some of the potential problems, check out one of my posts at Re: open with pipe) and afoken's reply. I gave a Linux example there, but the general idea will still apply to Windows.)