Will Typeperf do it for you?
This command produces output in a Command Prompt but you have to manually stop the stream of output via a Ctrl + C key entry.
typeperf "\Memory\Available bytes" "\processor(_total)\% processor time"
The output that I saw looked like this -
"03/12/2010 04:54:44.420","2767368192.000000","13.845755"
"03/12/2010 04:54:45.434","2767294464.000000","11.538048"
"03/12/2010 04:54:46.448","2767220736.000000","10.768817"
"03/12/2010 04:54:47.462","2767261696.000000","8.461109"
"03/12/2010 04:54:48.476","2767450112.000000","13.845755"
"03/12/2010 04:54:49.490","2767458304.000000","10.768817"
"03/12/2010 04:54:50.504","2767454208.000000","14.614985"
"03/12/2010 04:54:51.518","2768117760.000000","4.614942"
I am assuming that the last figure in each line is the CPU usage but I could be wrong there?
Typeperf
Personally I cheat and just type Taskmgr at the prompt to bring up the Task Manager but obviously the output is GUI and not in the prompt.