Lots of posts saying how to customize it, but it shouldn't be done,

Use custom content types instead and point them to a nice custom ASP.NET page instead

http://www.sharepointkings.com/2008/05/how-to-edit-list-forms-like-newformaspx.html
http://sharepoint07.wordpress.com/2008/02/05/customize-the-newformaspx/
http://blah.winsmarts.com/2007-5-Customize_the_-and-quot;NewFormaspx-and-quot;_page_for_a_SharePoint_List.aspx
http://vspug.com/dwise/2007/11/14/lesson-learned-while-customizing-newform-aspx/
http://www.risetime.com/blog/archive/2009/06/03/create-a-custom-newform-aspx-for-a-sharepoint-list.aspx
http://blogs.msdn.com/scaravajal/archive/2007/04/29/sharepoint-designer-and-newform-aspx.aspx

http://weblogs.asp.net/jan/archive/2006/11/06/Custom-Edit-Forms-for-SharePoint-2007-Lists.aspx

http://weblogs.asp.net/gunnarpeipman/archive/2009/06/05/sharepoint-customizing-dispform-aspx-and-editform-aspx-through-browser.aspx

http://nishantrana.wordpress.com/2009/01/30/read-only-field-in-sharepoint-editformaspx/