Did you resolve this Dave?
I'm back to LFS after a long absence and am struggling with the exact same problem. I'm experiencing a brief pause every few seconds and my network debug looks the same as yours although I've not tried changing the view to see if the interval goes positive.
I too have a dual boot Win 7/XP. Hardware is P6T Deluxe MB/i7 920.
I tried to update the ACPI device but as you found, the driver in use is the latest and there doesn't seem to be an update for this on the ASUS site.
When I first tried yesterday, I thought I'd start by killing a few processes. I killed two and tried LFS again and found the problem had gone. Tried killing the same two today and the problem has returned.
All other multiplayer games seem fine.