Man, do you keep all your components crammed up on a fairly small desk or something?
Subwoofer is under the desk, left and right speakers are about 15" to the left and right of the iMac ...
There's a difference between being magnetically shielded enough to keep from fuckin' up a monitor and being insulated enough from GSM to say, be powered by an iphone without having to resort to airplane mode.
Well, it's the iMac's built-in wifi that's causing the static (nice long bursts when downloading, short sequential bursts as it pulls in the pieces of a webpage) ...
It's too bad because I'm afraid you'll find that a lot of the sweetest speakers out there can be ran on a desktop but can't handle being next door neighbors with every wireless gizmo in the house.
So far I've managed to mitigate the problem somewhat by going old-school: wrapping the speakers in aluminum foil and popping ferrite chokes onto all the speaker cables

Those Logitechs will probably manage to do the job because logitech products tend to rely more on features and being hassle free than sound quality, so it's probably your best bet, particularly if you're like most people and really just want speakers that don't distort super bad when they're set to a decent volume. I have a friend with some z4s, and for Joe Onboard Audio they're the sensible choice; they've got a sub, they don't completely suck and they can sometimes be found for under $100. That said, my Audioengine A2s kick the living shit out of them, albeit for twice the money. Too bad they probably wouldn't handle the GSM interference any better than your Altec Lansings.
There's the rub. Just for audio quality, the Altec Lansings generally get slightly higher reviews than the Logitechs. And the Logitechs don't sound like they fare any better, I've seen a few reviewers admit to dropping ratings because of iPhone/GSM buzzing ...
A few other complaints on the net seem to indicate that the speaker cables themselves act as improv wifi antennas, the solution is shell out for speaker sets where both the speakers and the cables are shielded (which makes for a more expensive product obviously). The problem being that the majority of online sites and manufacturers don't bother mentioning those aspects of their computer speakers, they're too busy trying to convince you that they really are audiophile quality, really, honest, cross our hearts, would we lie to you?
