Random High Ping Periods

Hello, I was wondering if any networking guru's could throw me some possible causes to my problem.

In the house I have 3x Wireless G PC's and 1x Wireless G routers, PS3, XBOX 360, Wii, blue tooth keyboard and mouse and 3x 2.4Ghz Phones. Over the last couple of months I would get really laggy connections periodically (a couple of times a day). Normally my ping to say www.google.ca or a low ping TF2 server would be 30-40ms, during a "bad period" The average ping would be about 900ms. I also pinged the router at the same time and saw the high ping periods mirror. The bad periods would last from 3-4 minutes to a couple of hours. I've gotten fed up with the problem and bought a new 2.4Ghz Wireless N adapter (for my PC) and router (both ~$160). I'm still running into the same problem, which leaves me to think it maybe a collision problem in the 2.4Ghz spectrum (but I don't know enough about wireless stuff to really know anything).

I'm now contemplating upgrading to 2.4/5 Ghz simultaneous N adapter and router (for myself only cause everyone else doesn't do anything that a high ping would really affect). The gear is about $120 above what I've already spent but if it's going to fix the problem then so be it. Just want to see if anyone else has any insight into causes and solutions to my random laggy periods.

PS a neighbor (cranky retired old man) has a 3 story radio tower (about 75m away) which has interfered with our and other neighbors equipment (CRT TV and speakers) in the past. We actually looked into seeing if we could force him to take it down but he has a permit and there is nothing we can do. I'm not sure if this would have anything to do with it.

Update: I upgraded to a 5Ghz Wireless N setup and I still ran into the problem. I haven't had too much time to see the full extent yet though. My signal strength is normally 4 bars with all the hardware I've tried.