> However, with the notification that he can now pay me he also sends an email explaining that demands are not "fruitful" when it comes to business and that I should be more understanding when it comes to money issues.

What, you're running St. Victor's Consulting for the Destitute now? Let him see how far that attitude gets him with any of his other suppliers. Obviously your demands were "fruitful". He wrote the check, didn't he? :-)

>Was it wrong to give him the ultimatum or was in the right to do this?

I used to do it all the time. Granted, I tried to be a little understanding, but if it looks like I was going to be left holding the bag, well, I had plenty of other work I can do for clients that write a check when presented with an invoice.

> I have to admit to being a better programmer than a business man but I felt >that if he was gonna go under and/or "burn" us I'd make the debt be as little >as possible on my part. Any advice for the future when dealing with him.

That's what retainers are for. Get 'em to pay in chunks up front, and you never get burned. It's kind of hard to get clients to always go for it, though. My experience has been that it only works with clients with whom you have an established relationship.