Well, if you have the Enterprise edition of MOSS (trial version) installation, then you dont have to install a seperate form server. But if you have the Standard edition of MOSS (trial version) installed, then you'd have to install the form server seperately, however i do not know if you can obtain a trial version for the form server (you should run some searches about that...and see what you can dig up.).
My suggestion,
1. (if you have an Enterprise edition of MOSS) on your machine, is that you create a new form with just one OR two controls and try publishing it the way you want (as a test.), if you're successfull then you should build your main form again and re-publish it.
2. Check your central admin to make sure form service is configured:
'Configure InfoPath Forms Services'
1. Go to Central Administration.
2. In the navigation bar, click the Application Management tab.
3. On the Application Management page, in the InfoPath Forms Services
section, click Configure InfoPath Form Services.
4. On the Configure InfoPath Forms Services page, in the User
Browser-enabled Form Templates section, you can choose settings that
determine how user form templates are processed by InfoPath Forms Services.
Sorry, i don't know what else could be a solution at this point. But, i hope my suggestions can help.