How to send Windows Performance counters to Logstash + Kibana?

Elastic now offers a tool called topbeat that does what you're looking for. It sends cpu, memory and disk stats directly into Elasticsearch or into Logstash.

Example metrics are on github at elastic/topbeat.

The 'Tools that works with Graphite' page http://graphite.readthedocs.org/en/latest/tools.html list several. I have tried the PowerShell script 'Graphite PowerShell Functions' https://github.com/MattHodge/Graphite-PowerShell-Functions and it works well.

edit I mis-read your question, you were talking only about Logstash and Kibana but not about Graphite. I don't use Logstash+Kibana for system metrics, but I use Statsd+Graphite. So not sure if my answer is valid to you but if you use the Graphite Logstash input http://logstash.net/docs/1.4.2/ you could use these tools.