I appreciate you for joining the thread, @Sinclair. It's my pleasure to assist a loyal and valued QuickBooks user in our Community forum. I'll be happy to provide you with any additional information you require about your QuickBooks Desktop Enterprise 2009. 

I understand how relevant it is for you to easily upgrade your existing QuickBooks version. QuickBooks 2010 is the oldest version that is available for download for your QuickBooks Enterprise. However, you may create a backup copy of your QBDT 2009 company file and then restore it to the QBDT 2010 version. Before that, you must first find a license versions for the 2010 and subsequent year versions.

You may download it through this link: Downloads & Updates. Then proceed with the following steps below:

1. Click the Standard setup link.

2. Choose your product.
3. Select Version and scroll down to view the oldest downloadable version.

I suggest contacting our live support team for options and to help you manage your existing QuickBooks Enterprise edition. They have the necessary tools and equipment to handle your account securely and efficiently. 

If you wish to get a new QuickBooks Enterprise and experience the latest features, please see this article: Buy QuickBooks Enterprise, Purchase Enterprise Online.

If you have questions or need assistance with any QuickBooks-related concerns, please drop by again in the Community. Anytime you need help, we're available 24/7. Keep safe!