tcp/ip in linux 2.4 kernel

Hello,
	I have been searching for performance results of tcp/ip over GM on
the linux 2.4 kernel, we have been using the netperf tcp_range_script to
test our setup and can't seem to get performance above 1 Gb/s, we top out
at about 960 Gb/s, does any one know of other results on the linux 2.4
kernel?  I have seen the results from Trapeze and realize they use
FreeBSD and don't use GM, but still I imagine the protocol performance
difference should not be that great, our performance with UDP is quite
good, up to 1800 Gb/s.

Here are the stats on our setup:

Nodes:                                                                          
    Linux 2.4.5                                                                 
    gm-1.4.1pre10
    dual processor 800 MHz Intel PIII (Coppermine) 
    512 MB of RAM
    Myrinet 2000 switch,
    PCI64B, LANai 9, 4 MB SRAM
    SuperMicro SUPER 370DL3 Motherboard with the ServerWorks 
    ServerSet III LE Chipset.   

Pointers to answers are as good as direct answers,

Thanks,
Cam