Looking for research on automated, temporary passwords for new users

Hey all, have any of you had successful experiences with automated, temporary passwords being generated during the user sign up process?

I didn't read anything about this in  Luke Wroblewski's work and am looking for some insight. Our demographic is composed of many people in their 50's and 60's. I am looking to increase the ease of the signup process.

Do you think receiving an e-mail with simple instructions on creating a personalized password adds more trouble than benefits?

(In case it adds value to answering my question, at times, their account might hold credit card information.)

Thanks.

P.S. I have read the article here. Though they asked a similar question, the user base is much different.