an iso is a disc image
you need to burn it to a DVD or CD,
using iso burning software.
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In XP/Vista
1. Download and install Infra Recorder, a free and open-source image-burning program.
Infra Recorder : http://infrarecorder.org/
2. Insert a blank DVD in the drive and select Do nothing or Cancel if an autorun dialog box pops up.
3. Open Infra Recorder and click the 'Write Image' button in the main screen.
* Alternatively you can select the 'Actions' menu, then 'Burn image'.
4. Select the ISO/image file you want to use, then click 'Open'.
5. In the dialog box, click 'OK'.
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In Windows 7
1. Right-click on an ISO image and choose 'Burn disc image'.
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in a situation where you are not able to burn disc
you can unpack the iso using winrar
Winrar : http://www.rarlab.com/
then use the files that are unpacked..
if you possibly can.