Well I am new to this also, but I will venture a few comments.....

I tried a WUSB11 adapter and had no luck with it either. That is a USB 1.1 device so I assume you chose not to install the USB 2.? drivers from PTVnet? If not (and you did install the USB 2.? drivers) that is your problem. Oh wait.. I just noticed you did not mention using PTVnet.... Did you? You said you "copied my original drive".... If that is all you did you have no more capacity than you did before.... But I will assume since you are here on this forum you did use PTVnet and/or Instantcake..... They are really fine products, I am very happy with them

The whole wireless adapters deal to network Tivo's seemed too flaky and slow for me so I ran some CAT 5e wires through the walls and am using the Netgear FA120 adapters at the Tivo's and it works GREAT.....

I realize this is not possible for all, but if it is I would highly recommend it, much simplier hardware requirements and cheaper.... I think the main deal with using Wireless adapters is that you will need a "Wireless Bridge" also... the one I see recommend most is the WGA54G and that still requires a USB to Ethernet adapter (FA120). Or you can use a wireless router as a bridge, see this article...

http://www.dvrplayground.com/article/12254/

I hope you are seeing why I decided to bite the bullet and run the ethernet cables in the walls.... also what is more fun than being in an attic in Texas in August, during the day......

I hope I atleast gave you a starting point.