dropping wifi - Cured
Having started this particular thread I felt I should let you know that my problem has resolved itself completely now I have changed my wifi router.
I had a Linksys WAG160N router which worked perfectly OK with all my other kit - just not my ipad!
I have now changed my router to a BT HOME HUB and the problem has gone away.
I had tried everything with the Linksys including updating to the latest software from the support website, but nothing seemed to cure the problem. I don't understand why the BT Home Hub works where my Linksys didn't but I no longer care - It just works!!