x86 is not an identification for 32bit, that is a hardware platform. See release notes
http://www.vmware.com/support/vsphere4/doc/vsp_esx41_vc41_rel_notes.html
vCenter Server 4.1 supports installation on Windows 64-bit platforms only. If you have VMware VirtualCenter 2.x installed, see the vSphere Upgrade Guide for instructions on installing vCenter Server on a 64-bit operating system and preserving your VirtualCenter database.
keep in mind, vCenter 4.1 is 64bit and only supports a 64bit OS. Even if you aren't on 4.1, you should consider going to 64bit, which will make it a lot easier to upgrade to 4.1
Really?
But it does run on 32bit:
Processor – 2 CPUs 2.0GHz or higher Intel or AMD x86 processors. Processor may be higher if the database runs on the same machine.
x86 is not an identification for 32bit, that is a hardware platform. See release notes
http://www.vmware.com/support/vsphere4/doc/vsp_esx41_vc41_rel_notes.html
vCenter Server 4.1 supports installation on Windows 64-bit platforms only. If you have VMware VirtualCenter 2.x installed, see the vSphere Upgrade Guide for instructions on installing vCenter Server on a 64-bit operating system and preserving your VirtualCenter database.
Thank you Troy.
Thats clears it up for me.