Hi Guys,
Well good news I guess, its kind of all working now.
I removed the Realtek card from the HP and plugged a crossover cable into the RJ45 socket and ran this to the router. The HP can now connect to the internet and My Shared Files on my Advent PC. (This should keep the children happy as they can now do their homework etc)
My eldest sons Mac can connect to the internet via the wireless setup. (This should keep him happy)
My Advent can still connect to the internet via the router. (Now if everything keeps working and none of the above mentioned children don't break or destroy this system it will definitely keep me happy)
So I guess its time to give you guys a great big pat on the back and I can now go and pick up my guitar.
I somehow don't feel as though this will be the last time that I visit this site as I call my eldest son Digital. Oh well the sites now in my favourites (just in case).
@ John, Many thanks for those little commands you gave me

@Terry, I hope my post didn't confuse you too much, I'm not to good with these little electrical boxes, I much prefer the old wooden ones with just the six wires.
Once again a huge thankyou.
Best Wishes
JohnnyBeGood