slow cable connection

Im running an AMD Athlon 1.7gig and Windows 98SE with 640Mb RAM
I have Comcast cable inter service running thru a Motorola Surfboard 4100
modem and a Dlink router to 2 computers.

It has always prefomed quite well until about three days ago when I noticed things
running rather slow on my computer-ran a couple banwith test and sure enough,
I'm running at between 62kbs and 100kbs. It usually runs at 2500 or better.

Now here's what has me baffled- the other computer is kicking along just fine
running at 2700+kbs. I can switch cables,swap ports on the router no matter what
th one computer runs real slow (connection speed) and the other one runs just fine.

I have run several different spyware scanners (nothing found)
I've run virus scans (nothing found)
I've run System File Checker (all ok)
I've run scandisc and defragged
I've cleaned all cookies/temp files/history
the system all checks out fine
(here's the test results)http://www.pcpitstop.com/techexpress.asp?id=8AFTMWHSHJRSRG07

could the ethernet card be bad?
I'm stumped- and help/suggestions would be greatly appreciated