System Center / Hyper-V
Actually, your comparision between ESX Server and VMWare's management offerings to Microsoft's forthcoming stuff is pretty off the mark.
The Hypervisor is $28. The management software is System Centre Virtual Machine Manager and is a seperate product.
Let's face it, Hyper-V will be what everyone has when they migrate to Windows Server 2008 anyway. Give it a couple of years and it'll be standard. All MS have to charge for will be $500 for the "workgroup" edition of the management software - which covers 5 physical hosts. The enterprise edition is part of the MS System Centre Suite, which has backup software, management and operations software and auditing tools plus the VM management stuff for $1,290.
As per usual, the software probably won't be as good as VMWare or other companies - but it'll probably be cheaper and easier to use.