Hi Floid - many thanks for taking the time to reply to me.
Firstly, thanks for clarifying the termonology. To be quite honest, I wasn't entirely sure what it was I was referring to. That's why I called it the 'height'!
Regarding the mesh - would this
do? The spec says that the mesh is 2mm x 1mm.
It is also interesting that you reckon that I shouldn't get harmed by the Pc - admittedly, I've never heard of anyone else suffering. All I can say is that, when I sit at the Pc, my left knee is then about 6" away from the tower and I feel a low level buzzing or humming in my knee. A bit like it's being sizzled. Occasionally, if I've been there for quite a while, it starts to become quite uncomfortable. Just for clarification, I never feel this sensation anywhere else; only when I'm sitting at the Pc.
I'm sure it sounds odd but that is what I feel. So, that being the case, I decided I'd try out the Faraday cage idea if there was any chance of it working.
I'd really appreciate some feed back on that mesh I've linked to and, once again, many thanks for your help.