Macs network connection

I am having a small issue with my Network connections on a g4 imac. It is happening exactly the same with both the Ethernet and the Airport connections.

Bear with me a little as I am a windows head recently introduced to Macs

I am running OS X tiger and its fully up to date.

The problem is that my network connection performance drops every 5 seconds approx. At first I thought it was a wireless range problem, but the exact same thing happens with a wired Ethernet connection.

An example might explain it better. If I download a large file across the network, and monitor the network activity via the Monitor application (in the utilities folder) I will see my bandwith at 2.5 Mbits/s for about 5 seconds, then it drops to 1 Mbits/s for a second and then back up to 2.5 for another (approx) 5 seconds, and then down to 0 for a second and so on. Doing the same on a PC connected to the same router, will show a constant 2.5Mbits/s and hence a quicker download.

Its NOT a network problem. My network is correctly setup. There is nothing else using the network when thsi happens.I do not have the same issue on any of my PCs (and I have a few ) I have tested this vigourously over the last couple of days.

I have set up my ethernet and Airport connections correctly (as far as I can see) using System Preferences> Network. I have tried both DHCP and Static IP addresses, but no difference. The Firewall is stopped for all the items in the list.
Am i missing something? Are there an settings/ Utilities that are not obvious that could impact this? Has anyone else seen this.



Any help would be appreciated

Dil