How do I change File extensions in Windows 7

[Shaan12]

Okay well I am new to this computer world.
I have DL'd 7600.16385.090713-1255_x64fre_client_en-us_Retail_Ultimate-GRMCULXFRER_EN_DVD and it shows up as a 3Gig html file on my desktop. I've tried renaming the file with an .iso extension so I can burn it but it still shows up as an .htm file.
Is anyone aware of how to do it.?

[Macarenas]

Well it's pretty easy, don't worry.
But before that can you tell us like which Operating System are you using currently.?
Because everything depends on the Operating system you use, so that you can get the proper guidance and will be able to sort out this issue.

[Shaan12]

Okay the Operating System which I am using currently is Windows 7 Ultimate 64 Bit Edition.
Before I was using Windows Vista Home Premium 32 bit edition. Which I then formatted and installed Windows 7 and I am really very happy with this Operating System and everything is working fine over here, except for the file extension. But I guess that is not my Operating Systems fault.

[ZeDaX]

Just follow the steps given below and you will be able to change the extension.
Click on Tools -> Folder Options -> View (Tab)
UNcheck "Hide extensions for known file types" -> Apply
If for some reason the actual extension is .ISO and your ISO files are associated the same as HTML files, you can right click -> Open With... and choose your CD burning software.
Alternatively, you can get a program called Types to manage your file types.
And I'd recommend ImgBurn to write CD/DVD images. Both are free.