Alot of the time I check services through the services manager ("Start" > "Run" > "services.msc"). That's all fine and dandy if you just want to start/stop/disable them, but if one goes rouge and hogs up your memory or cpu time, the Windows XP "Task Manager" wont show you what it is (unless you're running Vista, but I'd rather use LinuxMint).
All that it shows in the Task Manager are a bunch of "svchost.exe" processes. These executables provide a common entry point to execute services (in either DLL or executable formats).
So if you need to know what service resides within the "svchost.exe" which is causing you problems, go to Task manager and then "View" > "Select Columns" to ensure that PIDs are showing. Keep the task manager open.
Then open up command prompt and type "tasklist /svc" to list all services. Find the service information by matching the PID from Task Manager.