LinkSys Router Speed Problem

[skincer]

When I connect my cable modem directly to the Ethernet card in my computer, I get speeds around 1400Kbps Down / 275Kbps Up. When I connect the cable modem to my LinkSys router and my computer to the switch built into the router, I get download speeds that are roughly 1/10 the speed when I'm not going through the router. Can you give me any ideas of things to research or try?

I have a Pentium 200 computer, 128MB RAM, running Windows NT 4.0, my ISP is Cox@Home, my cable modem is a Toshiba PCX1100 although I had the same problem when I had a Motorola cable modem).
Thanks.
Steve

[ssjDoh]

Hmmm, did you install the latest firmware? And what's you NIC?

[skincer]

The firmware is version 1.3 (not the latest, but pretty recent). LinkSys says all over their web site not to upgrade your firmware to correct speed problems, but only to take advantage of new features. It may come down to trying this, but I have a gut feeling that this won't help. My nic is a 3Com Fast EtherLink XL Adapter.