I wouldn’t open an entirely new account for Evernote and GTD. It is best to just set up a specific notebook for it — and have that be your default notebook. You could have a separate notebook for your reference items and clippings, or just use the one notebook with a very specific tagging system. The latest Evernote browser extensions will allow you to easily choose where you want to put the item you are clipping. You can also search your notebooks and tags directly from the extension and view whatever item you like — it will pop up quite quickly in a new window.
Another option for you would be to investigate running Evernote desktop from a USB thumb drive. This option was offered in the older version of Evernote, but there is a workaround for the new version. Check this link here: http://bit.ly/4Qg0O9. Make sure you read the first few comments for the workaround and issues/concerns regarding it.
Hope this is helpful! :D