1. Open the case, remove the HDD. There may be screws or a sliding clip that holds it in place.

2. Set the little jumper on the back of the drive to 'slave' before putting it in the other PC.

3. Open the other PC and connect it to the (probable) trailing ribbon connector (about 2 inches wide) and connect one of the spare 4-pin power cables. You won't have to fit it in the case just balance it on something non-metallic, e.g. a shoe box.

4. Boot up and Windows will find the drive and install it.

5. Open 2 explorer windows and drag/drop your files from the old PC to the new.

6. When you have copied them all, switch off and remove the old HDD.

7. Now boot up the 'other' PC and make further copies of the files you have just copied, to say, DVDs, CDs or some other external storage. This will give you the added security of a second copy of your files in case the 'other' PC misbehaves.