In Windows XP, Task Manager is like the dashboard of a car. It's your interface into what's going on under the hood. It can tell you things such as: what programs are running in the background that you can't see, how busy the processor (CPU) is, which programs are making the greatest demands on the processor, how much ram is free, the number of hard disk reads/writes by each program, etc. etc. When your computer is running slow, or seemingly frozen, Task Manager should be the first thing you turn to.
For whatever reason, Microsoft has hidden Task Manager. If you look for it in the usual way, Start -> Programs, it's not there. It should be under Accessories -> System Tools, but instead Microsoft included the Character Map program.
Since Task Manager is both useful and hidden, I suggest having it run automatically when Windows starts up and instructions for doing this follow.
The end result of the steps below is a dark green square in the system tray (a.k.a. notification area). If the square remains dark green, the processor is on a virtual coffee break. The box is like a vertical bar graph, where light green on the bottom indicates how busy the processor is. If the bottom half of the box is light green, the processor is using half of its total capacity. If the square turns entirely light green, the processor is running at 100% capacity.
One warning that your computer might be infected with something malicious (virus, spyware, Trojan, etc.) is that processor is busy when you're not. That is, if you are not running anything on the computer and Task Manager indicates the processor is consistently more than 10% busy (give or take), it's worth looking into, to see which program is using the processor.
Running Task Manager at System Startup
In Windows XP, right click on the Start button and select "Open All Users". Then double click on the Programs folder, then double click on the Startup folder. Minimize this instance of Windows Explorer, we'll return to it later.
Open another copy of windows explorer and navigate to
Right click on the taskmgr.exe file and opt to '"Create Shortcut". Then right click on the shortcut you just made and Cut it.
Go back to the first instance of Windows Explorer (positioned at the Startup folder) and Paste the shortcut into the Startup folder.
Although not required, I suggest right clicking on the shortcut and renaming it "Task Manger". Then right click on the shortcut again and get the Properties. Change it from running in a "Normal window", to running "Minimized" and click the OK button.
Next, double click on the same shortcut to run Task Manager. It should show up in the system tray. Open Task Manager and on the Options menu, turn off "Always on top" and turn on "Hide When Minimized".
There are many data items that Task Manager can display. To see them, from the View menu, select "Select Columns...". It defaults to showing the User Name which I don't find useful. I suggest adding the "CPU Time" column to see the total CPU used by a program (technically a process). The column labeled CPU shows only the current CPU usage.
Click the OK button when you are done selecting columns. If you like, you can change the sequence of the columns in the display just by dragging the column heading.
Restart Windows XP and you should see the dark green box in the system tray. If not, join the crowd. I suspect this is due to a video driver bug, but it may be a Windows bug. I've seen it all too often.