I had another forms package on my Joomla! 1.5.14 installation but it just didn't quite cut it.
Mad4Joomla Forms sorted it all for me :)
The learning curve was a little more steep that I would have liked - but I am now assuming that this is due to a timing issue on my server and not with the plugin as I am having a few hiccups.
1. I can't put any text in the Maintext field of the form definition. If I do - the update/creation fails silently.
2. Every time I click on 'New Form' or Edit an existing one ; I get an unformatted page starting with 'ss/template.css" rel="stylesheet" type="text/css" />' - A refresh will fix this quite happily.
All in all a superb forms package that got me up and running in a few minutes. The hiccups I believe are down to my host and so I give an excellent rating.