Cannot download iTunes

Hi, I have the XPS M1530, with Vista Home (Premium, I believe) and I cannot download iTunes. I keep getting a Microsoft Windows box that says, "A problem caused the program to stop working correctly. Windows will close the program and notify you if a solution is available."  It then gives me a message saying that I have to, "Change Data Execution Prevention settings" which I added iTunes - still no joy. I've uninstalled iTunes and reinstalled it a few times and still no luck. It wouldn't let me save it to my Programs folder saying that I didn't have Administrative Access - but my computer settings say that I do (I'm the only user of this lovely machine). Thoughts?

Thank you for any assitance!