No, from versions 2.2 forward, MongoDB has not supported Windows XP.
What do you mean by finding the execution time of a query on the command line? How are you running the query? You could use a timing utility to time a short mongo shell script like
mongo --eval "db.test.find(); quit()"
but you're timing a lot more than the execution of a query since it counts, e.g., the time to set up the connection. For timing information it's better to work in a script or program using a driver or use the built-in profiler to collect statistics server-side.
-Will