WatiN browser not displaying PDFs in browser

I'm developing some tests for a website that contains some PDF content. The instance of IE8 created by WatiN does not open the PDFs in the browser, instead asking to download the file. When I examine the list of add-ons for this browser instance, it does not list Adobe PDF Link Helper (it only lists Windows Messenger). When I open IE8 manually, many add-ons are listed, including the Adobe PDF he开发者_StackOverflowlper. Any idea how I can get the WatiN browser instance to recognize the missing add-on?

Thanks.

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I determined this occurred because I've running the tests on Windows XP 64-bit. When I launch IE from a shortcut, it is run in 32-bit mode. In this mode, all the plug-ins are available (including Adobe Reader). When WatiN launches a browser, it is running in 64-bit mode, which doesn't have the plug-ins installed.

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Changing the Build Configuration of the project to 32 bit solved the problem.