augieboo, I'm no expert on this, but I have an experience like you described a year back. What I found out was the incompartible setting of modem speed and the router speed. Back then, I had my old router set to 100 Mbps, not knowing the modem from the phone line can only handle 10Mbps. Check your router speed and the modem speed. I think they need to be the same unless your router is smart enough to detect the source speed. Next check your netwrok card speed. Most of the new network cards are now equiped with autosensing. That should be all right.
I am with PacBell DSL for more than a year, most of the time are quite stable. They gave me an Alcatel 1000ADSL modem which is only 10Mbps, I bought my Linksys 4 port router (autosensing).I have couple PCs hook up to the router. They work fine so far.
If you have gone through this before, then I have no other suggestion.
Hope this help!
Cal