Effectiveness of suppresion magnets?

[Mickey Juice]

Hey peoples,

I recently aquired a 2 ch 100W car amp from eBay and i've got some suitable kenwood, 3 way 6x9s... The only problem is if I get the speakers anywhere near my cab (cocktail cab with 17" monitor) the monitor screws up.

I see the best shielding solution is to attach some donut (feritte bucking) magnets to the back of the speakers.
How effective is this? Will there be any more magnetic interference? Esp. with one of the speaker being close to the mobo/HDD.
I don't want to go to the trouble of ordering some magnets and it turns out to be ineffective.

or should I just buy some decent powered PC speakers and put the others in my car?  

[MnMCaputo]

I'm having an issue with my car stereo speakers in my mame cabinet as well, i'm thinking of buying 3' of this stuff
http://www.lessemf.com/mag-shld.html

[Wenis]

I had the same problem in my mame cocktail and I bought some Bucking Magnets http://www.partsexpress.com/webpage.cfm?&DID=7&WebPage_ID=3&ObjectGroup_ID=571&SO=2 from here and they work great you just put them on with glue.

[Mickey Juice]

So you've got *no* problems at all after using the bucking magnet?

[Wenis]

That is true the magnets fix it 100%