"This installation package is not supported by this processor type." when installing vCenter 4.1

You are trying to install/upgrade vCenter 4.1 on a 32 bit host.

vCenter 4.1 only supports 64 bit Windows architectures and will no longer install on a 32 bit host.

You will need to migrate your vCenter Server to a 64 bit OS. Please see the following tutorial:  Using the Data Migration tool to upgrade VMware vCenter Server 4.1

Have you find the release notes on the downloaded iso or zip file ? they are not included in the downloads !
VMWare should change the box in "you need 64 bits processor" so do't shoot us shoot VMWare fore there misleading info box.

I love this dialog box. But I think the text should be changed to... "Look you bozzo, why don't you take the time out to actually RTFM the release notes before you get started. Have you consider an alternative career - ideally one not in IT?" hee-hee-hee