It's not the driver or the OS?

Read http://forums.cnet.com/5208-21565_102-0.html?messageID=3166122&tag=forum-w;forums06#3166122

"2 Apple engineers from Cupertino (like a visit from royalty!!! -fortunately in my area for someone else) were at my house last week troubleshooting for 3 hrs! They were very professional & helpful. Determined that the at&t 2Wire Gateway 2701HG-B router was dropping outgoing signal. They did data capture tests & showed me screen image indicating strong incoming DSL, but unstable outgoing from the router portion. Said they've heard of lots of similar issues w/ that modem/router which at&t still provides to new DSL account customers. They suggested I disable the router portion & hookup with new Airport Extreme router (or any newer router). Did it last night, so far no more unstable wifi! AE even works great for the Vista laptops here, altho they are type 'g' versus my iMac being type 'n'. It sends out separate signals for each type. Apparently the Snow Leopard timing was merely a weird coincidence. Whatever, I'm very happy w/ Apple again."

This is a fine example where owners must maintain an open mind that it may not be their computer at fault.
Bob