I am running Windows 7 x64 and I downloaded the client directly from my vCenter's website (or ESX host) https://<hostip>/client/VMware-viclient.exe. When you say that you download it and try to install it, it fails, correct? Make sure that you have no traces of it installed. Prior to installation you shouldn't have a "C:\Program Files (x86)\VMware\Infrastructure" folder. Unfortunately, with 4.0u1 I had no problem with the client running directly under Windows 7, the release notes stated that it now works correctly in Win7.

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