Fried Motherboards & Cable Modems??

Ok, this is for general discussion...I don't know how many of you have ended up with fried motherboards in the past but recently my brother's computer at home, which I built, has had 2 fried motherboards within a 4 month period. I don't feel that it is necesary to list all the specs because I think that this has to do with some kind of power surge. This was a pain in the neck because we had the power company come out to test for power spikes and they found it to be normal. Then I got to thinking of what else it can be and I realized that we got a cable modem last December and the 2 boards fried during that time period from March - July of '02. I talked to someone at APC and they said that it's not uncommon to receive power spikes through cable modems. So after he bought and installed another new motherboard, my brother purchased a APC UPS backup under my recommendation. The model he bought was the VS500 which has surge protection for broadband conenctions. So far this has worked and no fried mobos.

I'm wondering if anyone has had or heard of these problems and if the UPS will hopefully solve the problem. APC has a 2 year warranty on all its UPS's so if anything fries in the future they will pay for all components damaged.

here's the link to the UPS we bought...

http://www.apc.com/products/family/index.cfm?id=28