Microsoft has released CRM 4.0 Update Rollup #7, this is one of the major update that you don’t want to miss.
The outlook client is completely re-engineered. It resolved a ton of issues related crashes, etc… If you like to know more, please read more on the Microsoft CRM team blog.
http://blogs.msdn.com/crm/archive/2009/10/22/update-rollup-7-for-microsoft-dynamics-crm-4-0.aspx
To download the client, just click on the link below.
The Microsoft KB related to this rollup is below.