I would most certainly look into Infopath Designer.
Though the variants of how to do it (in browser-enabled or client forms, with logic inside Infopath form or outside of it, etc., etc.) depends on your requirements and Sharepoint configuration (really a few dozens specific questions).
(after reading comment to another answer "We're running Foundation, so Infopath isn't an option"):
Infopath is still more than viable option if you are running Sharepoint Foundation.
You simply will not have ability to run browser-enabled Infopath Forms through Sharepoint Infopath Forms Services. This does not imply that you wouldn't be able to publish Infopath forms or launch them from Sharepoint in browser.
They will be simply lunched in locally installed in each client Infopath instead of in browser on the basis of Enterprise Sharepoint Infopath Foems Services.
You would just confine to having every client to have Infopath installed locally and using Internet Explorer for Infopath forms.
But client forms are more rich than browser-enabled forms and permit custom code (that is not available for browser-enabled Infopath forms), et.c, etc.