If you are planning to move to SP2/R2 SP1 or even installing a new environment you should be aware that Microsoft changed the minimum recommended hardware requirements.
Microsoft doubled the amount of memory you need in your box and increased the needed amount of disk space. You can find a quick overview in the below table which is not complete!
|Installation type||CPU||Memory||Diskspace||Max Clients|
|Central administration site with the Standard edition of SQL Server with local SQL||8 cores||64GB||1.5 TB||400.000
500.000 (with CU3 and up)
|Central administration site with the Enterprise or Datacenter edition of SQL Server with local SQL||16 cores||128GB||2.5 TB||600.000|
|Stand-alone primary site with local SQL||8 cores||32 GB||550 GB||100.000|
|Stand-alone primary site SP2 with local SQL||16 cores||64 GB||900 GB||150.000|
You can find all the new requirements on their TechNet WebSite.
So be aware on how the environment should look like when you upgrade or deploy and have fun ordering new resources 🙂