Hello Rik,
With XP, left click on the Start menu and then on Control Panel. Then double left click on System.
The System Properties window opens and will tell you your version of Windows - eg XP Service Pack 2.
Further down it will tell you about your processor - eg AMD Athlon Dual-Core Processor 5200B.
The processor speed - eg 1.79 GHz
The amount of memory - eg 2.87 GB RAM.
Depending on your machine it may add a few more details as well.
When finished, close the window.
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Also left click on the Start menu and then on Run.
Enter dxdiag into the Run window and left click OK.
If it asks to access the internet you can say no. If you say yes you get more up to date information but only on obscure stuff you're not interested in right now.
The DirectX Diagnostic Tool window opens.
The front page has information about your operating system, processor & memory again and various tabs along the top reveal other information - most of which more than you need to know.
But Display will tell you about your graphics card - eg NVIDIA GeForce 6150SE nForce 430.
And the graphics card's memory - eg 512 MB.
Select Sound for information on your audio system.
You can even save a copy of all the information.
Go back to the front page by left clicking the System tab at the top left.
At the bottom right is a button titled Save All Information. left click this and it creates a plain text file of information which you can then save where you want.
Exit the window when finished.
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And there you have the basic stats of your PC!