KB 977650 Update Rollup 9 for Microsoft Dynamics CRM 4.0 was released on February 11th, 2010 and is available for download at http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=5869f2b3-d1a0-4f71-8be3-fde6e8053a2e

Update Rollup 9 contains a cumulative set of updates and hotfixes for Microsoft Dynamics CRM On-Premise. For more information see Article ID 977650 at http://support.microsoft.com/default.aspx?kbid=977650

I’d suggest reading the 977650 article before getting started so you understand what’s involved. There are prerequisites including Update Rollup 7 and special considerations regarding Office and Exchange 2010.

As always, I’d suggest doing a full backup of MSCRM databases and even exporting customizations as a precaution. Update Rollup 9 can be uninstalled but it’s better to be safe in case the uninstall has a meltdown. Also, I’d suggest installing this in your test environment and then testing for server and user issues before implementing it in your production environment.