Windows 7 Failed installation

[matata]

My desktop is adequate for W7. I have downloaded Windows 7, burnt a CD from the downloaded file using an Iso burner but after stating burning was successful the following message appeared. Bad image. The application or DLL F:\Sources\SPWIZENG.DLL is not a valid Windows Image. Please check this against your installation diskette" Can anyone help please?
Gordon

 

[matata]

I downloaded two copies (one after the first failed) from the Microsoft site. It was RC 2. I burnt at the lowest and second lowest speeds. I tried a CD followed by a RW DVD. Will it make a difference which type of disc is used?