there is another FD thread on this very subject from just last week, here: http://members.founderdating.com/discuss/927. 41 responses.
@ Archer, i would recommend reviewing the same thread.
You can see my longer responses in that thread. in short:
1. NDA's have their place. this is one of them, IMHO. i would if i was you, especially if you are considering patents. If these "5 -6 interested people" are individuals then it's that much easier. if you are expecting their employers to sign that will be a longer road to get through their legal dept.
2. Customers respect your desire to do things right, Their employer would do the same, so don't think that by asking you are putting too large of a burden on them. Don't think that any tech company of any size does not required NDA's if they entertain discussing prototypes with their customers - they do.
3. An NDA doesn't protect your idea from being disclosed so if disclosure can cause a real problem then don't disclose. An NDA, like a patent, only gives you a basis for legal action. Don't ask anyone you don't trust to sign and NDA. One reason to use an NDA is to set the tone for discussions of potential business transactions (a partnership, employment, M&A, development, etc.). Our NDA is a "Mutual NDA" which is often more palatable as it puts both parties on the same footing: "you don't disclose my confidential information and i don't disclose yours".i am happy to share our version with you and you can modify to fit your needs.