Thanks for the reply.
It's an HP 640n AMD 64 3400+ 2.19mhz
Idle, the memory shows 540 available. I don't have anyone to call at the moment, but will try to see what happens to the memory while incoming sound is hitting it.
As I rather clumsily said, when others call me, the problem is there, but nowhere near as bad. A pal in Ireland is sometimes so clear that I can hear him breathing...(and his mike is not near his mouth! ) But then, the noise will start to the lesser amount.
I did go to CompUSA or whatever it's called now, and the price of memory was so high - because it was old - that I backed off that idea. Pity, I'd recently upgraded my disc drive with the last of the old type...wish I hadn't now. However, in all other respects, I'm really pleased with this machine.