Sorry to bang out a 1st post with a question, quite rude I know. Let me introduce myself first.
I've was a dedicated Q3 player for several years, I kinda pulled away from it early expecting D3 to offer "The next big thing", boy was I wrong and do I miss Q3. Tinkered with Painkiller but online sucked, played CoD but thats not the same type of game. So now I'm here with Quake 4. SP was better than I expected and the online seems to be more of what I loved about Q3.
However, I have a problem. My lagometer gets yellow lag spikes at about 1 second intervals. This gives me packet loss like jumps and stutters and makes playing online impossible. Forum searches are of course full of the terms Lag so its been hard nailing this down. Now with the 1.1 beta out I feel confident its not a software issue so would really appreciate some points on where to look next.
My System: I won't go into huge details but its a X2 4200+ CPU, 2gig ram, 7800GTX GPU etc. Router is linksys WRT54GX2, PC connection to router is wired.
Tests:
I've run a local server and it works fine, no lag.
Moved networks menu setting from DSL/Cable to ISDN with no difference in the lag spikes
Swapped the network cards (NF4 mobo so both built in net cards)
Tried multiple, low ping, 0 player servers and done nothing but stared at walls.
Used lagometer in CoD and not seen the same spikes.
Thoughts:
I'd be thinking something crappy on my network end if it wasn't for the CoD test not showing any spikes. I'm on Bellsouth ADSL 2.5meg, nothing great, perhaps some packet loss but the regularity of the spikes suggests something else I think.
Piccy:

Thanks, I'm crossing my fingers you can give me some fragging fun this weekend.