Essentially:
1) God commands us to worship him as he has purposed, not according to our inventions, the "doctrines and commandments of men," "will worship."
2) Because of this, we need to search Scripture for what he commands.
3) There is explicit command to sing Psalms, as well as example, but no such examples of hymns etc. Col. 3:16 appears to be discussing Psalms, but if it does include hymns and modern praise songs, modern praise songs especially have failed to live up to the verse by not really teaching or helping us hide God's word in our hearts.
4) Verses describing instruments do not refer tot eh corporate worship, and they have passed away due to their connection to animal sacrifices.
5) In summary, we are to "worship in Spirit and in truth," "making melody in our hearts to God" instead of using external "helps" like instruments since we no longer need them.
http://www.evertek.net/giwopc/rpw.html
http://www.apuritansmind.com/PuritanWorship/McMahonRegulativePrinciple.htm
http://members.aol.com/Puritanone/instr.htm
http://reformedonline.com/view/reformedonline/psalm.htm
http://www.reformed.com/triangle/t_psalms.html
http://www.fpcr.org/blue_banner_articles/eph519.htm
http://www.fpcr.org/blue_banner_articles/worsong.htm
http://www.the-highway.com/psalmody_Irons.html
I don't have the time nor desire to write a long speel on the matter, but there you go. Enjoy your reading.
This is a false dichotomy. In many churches if there was no organ or piano all the singing would be off key.