Ok. spent about 5 hours today trying to sort this problem out and in the end finally sorted it out!

Like to thank warwaste for all his ideas and must say it helped me solve it in the end!
I first tried ethernet cables but didn't make any difference. Checked the SSID and all of them were set correctly. Found the AP isolation but it was turned off anywhere by default so that blew that idea. Tried turning off the firewalls on both the router and then the firewalls SP2 on each PC, again nothing seemed to work or make any difference!

Then made sure all the correct protocols were installed TCP/IP, Microsoft file & print sharing and then IPv6. Only one which I hadn't installed was IPv6. After doing this I could finally see each of the PC's...progress..couldn't open them with the file/print shares I had made on each but at least they were showing up as icons...

Mucked around for ages, trying different things, making new shares, checking connection settings etc then finally saw that the Pc's has internet sharing ticked...hmm..shouldn't need this as they each individually can get the internet thru the wireless router/adsl...unticked and restarted the PC's and everything worked fine and shares and printers all could be seen!!!!

So there you go...installed IPv6 and unticked internet sharing..such a simple solution in the end but hours of searching to see why it was not working...

Anyone have any ideas why this would do this anyway??

PS: Thanks for your ideas/reply Warwaste!!!