dan-572483 (12/4/2012)
I would say anthing with at least 12GB of RAM. That way you can run VMs for a domain controller and two cluster nodes without having to wait an hour between clicks.
You don't need that much RAM. I have 8GB of RAM and I could study for the exams just fine.
For the DBA exam (where you'd need the most virtual machines) the maximum count of servers that need to be running at the same time is 3. (two clustered servers and a domain controller). This is 2GB RAM for each of the servers (the domain controller can work with 1GB as well) and 2GB for the hosting environment. You don't need to run heavy stuff on the servers anyway.
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