I'll start with the Luccio thing. She states clearly that she reads about computers when questioned about her hobby. To take her not specifying that she only reads as proof that she does more, would be entirely illogical. There's no sensible reason to assume that because she didn't specifically say otherwise when implying otherwise, that she uses computers. She's not a fey dancing around words. She's a human with no reason to hide her ability from Dresden, especially in the context given by the book.
As for the wizard ability to use computers through the water room. To properly fully drown out all magical ability with water, every case given in the book has the wizard IN the RUNNING water. Still water doesn't really do much of anything if anything and just being around the running water only hampers magical ability - it doesn't stop it.
So, to fully protect the computer you'd have to have the wizard in running water while using it (comfortable, no?). The peripherals would need to be waterproof for that reason and then all of these costly and annoying measures should allow the wizard to check his or her facebook for a while until the pumps that keep the water flowing over the wizard eventually give out. At that point you hope the wizard has implemented many redundancies.
As for magical Faraday Cages,
One was shown in Turn Coat and it pointed out that more like a surge protector, it only works once. After the one hit, it's gone.
Then again, we have Mac's which uses many random occurances of the number 13 to put up a magical umbrella. That would probably be enough to throw off SOME of the magical energies but hell, if I recall correctly, Mac won't even use light bulbs because of the massive expense. This leads me to believe that nothing short of massive amounts of complex anti-magical redundancies paired with a lot of expensive technological redundancies for those occasions when things just fail (because that happens even without magical need. Come on, it's computers) would be pretty much the only way to allow a wizard to use a computer reliably.
Just for the record, this would all leave the wizard more or less magically naked. Weak. Defenseless. Sure, you might be able to put together a work-around but bare in mind that all these work-arounds and redundancies take up time and money as well as, in all likelihood, some enchanted item slots and the like. At what price Technology?