EDIT: This article seems to be popular, however readers should note it is from 2011!  Check out the updated article here:

Upgrading DirSync to the Latest Version

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As Microsoft has already stated, the new 64-bit version of DirSync.exe is not installed or configured differently than its 32-bit predecessor.  However, as a tinkerer, I wanted to verify this and have a look under the hood anyway!

Below are some screenshots of my experiences and insights along the way:

Before you start: Read and follow the instructions!  In this article, I assume you’re at the point where you’re actually ready to install this product.

1. First I installed the .Net Framework prerequisites as well as my favorite MMC snap-ins onto a new Windows 2008 R2 server. You can do this using the following two lines in PowerShell	Import-Module ServerManagerAdd-WindowsFeature NET-Framework,RSAT-ADDS -Restart
2. Then I ran dirsync.exe (downloaded from the portal.microsoftonline.com site).a. NOTE: Microsoft didn’t bother to change the installer’s executable name (dirsync.exe). This may be confusing if you plan to download and store both x86 and x64 versions.
3. A few clicks of the “Next” button…
a. NOTE: We install to the “Program Files” directory. If this were a x86 application we’d be using “\Program Files (x86)”
b. NOTE: This screen may take 5-10 minutes. It’s installing a few things in the background:i. SQL 2008 R2 Expressii. Forefront Identity Manager 2010 (FIM)iii. Configuration of the FIM Management Agents (MAs)
…
4. Once the background tasks have completed, you’re able to run the Configuration Wizard. This is where you will need to have your Office 365 tenant prepared and credentials identified, etc.
5. Next…
6. You should have created this account earlier. Whatever you put in here will be stored within FIM, and if you ever change the credentials, you’ll need to re-run this setup wizard.
a. Or for the expert user: Dive into FIM directly
7. Here you need to supply your forest’s Enterprise Admin credentials. This username is not saved anywhere, and is only needed once to set permissions for these new objects:a. Yourdomain\MSOL_AD_Syncb. Yourdomain\MSOL_AD_Sync_RichCoexistence
8. Selecting this box enables some extra features required for a “hybrid deployment” / “rich coexistence”, and by doing so you’ll allow FIM to update attributes IN YOUR Active Directory. If this box is not checked, FIM will read-only.
9. Next..
10. If you’re ready, you can run the initial full synchronization now. Otherwise, you can run it manually at any time.a. Once configured, DirSync runs every 3 hours.
11. If you promise to be careful, you can poke around in the FIM configuration. a. Note the “hidden” client UIb. If you get an error when opening the FIM console, log out and then back in. Your account was added to some groups that are not yet part of your login ticket.c. Clicking the Management Agents tab shows both sides of your configuration. “TargetWebService” is responsible for all of the Office 365 configurations and the “SourceAD” management agent contains your Active Directory connector information (double-click them to open).NOTE: Changing the DirSync configuration directly within FIM is unsupported by Microsoft. They would prefer you rerun the previously mentioned Configuration Wizard if you need to make any changes.	C:\Program Files\Microsoft Online Directory Sync\SYNCBUS\Synchronization Service\UIShell\miisclient.exe
12. Finally, be sure to run Microsoft Update again. You’ll notice that SQL 2008 R2 does not have SP1.