Long story short, you need to increase the level of the statistics that vCenter is collecting. Doing so will dramatically increase the size of your vCenter database, but will give you access to a larger set of tracked values.
Read the administration guides for vSphere (4.1, chapter 9 and 4.0, chapter 22). These will show you how to increase the logging levels, and what stats get kept at each level.
Once you increase the levels, you'll need to wait until the statistics roll up jobs get run before the additional counters are made available in the vCenter performance tab. Given that, don't worry if it takes 24 hours before you get the ability to select them.