I have an Internal DVD burner that is not working, and I bought an external. How do I get the DVDSP or the OS to burn to my external, not the internal?

TIA!

Use the Format or Build/Format command instead of Burn. DVDSP will let you choose your output device (if you had a DLT or something else attached then this would show up in the list as well). If Mac OS recognizes your external burner then it will be one of your options.