Bidirectional ethernet cable/wireless router question...problem

And your question was?

I have recently setup a network at home. I have the NetGear WGT624 103mbps router and installed in my son's computer a WG311 wireless card. Ever since configuring our network we have been experiencing slower throughput speed readings. I have a 1.5mbps DSL connection through Verizon. If I go directly from the DSL modem to my computer I get fairly steady 1200-1390kbps speeds. While running through the router, even with other computer off, I get slower, varying speeds from approx. 600kbps up to around 1175kbps. My question is this, is there a(need for) bidirectional ethernet cable to possibly stabilize my throughput speeds? Or is this possibly just my ISP? I've heard they have been clogged lately. I've done the recycling thing often, emptied cache/temp/cookies etc. all to no avail. Occasionally it stays fairly steady but for the most part it is slower than my liking or expectation. For what I pay for my 1.5Mbps connection I want better. I am within 3500ft of the Verizon station. My son's computer is less than 20ft away and only transmits/receives through a doorway, no blocking wall. My new computer is a DELL 2.8Ghz P4 w/800MHz HT FSB, 1GB RAM etc. The older one is a T700r Dimension, 512mb RAM etc. Both operate extremely well. Yes, I have been on the phone with Verizon Techs, for what it's worth they say I am getting readings within my 75% range of advertised speed package.
Sorry for the long post. Any advice or tips are much appreciated.
Frustrated
Rick

Well, this obviously sounds like a router problem - you've done all the right trouble shooting. NB: All ethernet cables are bidirectional :). I would tru swapping out the router.