[tulip] Slow Linksys Etherfast 10/100 PCMCIA speeds

[sc]

Hi,

I'm at my wit's end trying to figure this out; so, this newbie is 
throwing himself at the feet of the community to see if anybody can toss 
me a clue.

My setup:
- Debian 2.2.17 on a ThinkPad T20 with a Linksys 10/100 EtherFast PCMCIA 
card.

Problem:
- Slow network speeds 5-10 KB / s on multi megabyte file exchanges.  File 
sizes < 400 K work ok but performance takes a big hit afterwards.

I'm guessing that the potential causes are:
- tulip.o driver isn't working properly.
- the card is improperly set (say to full duplex rather than just half).
- hardware-related conflict like an IRQ snafu.
- didn't sacrifice enough hamsters.

My troubleshooting efforts:
- works fine on the Win98 partition
- ifconfig is showing a large number of collisions : 10-17% of RX packets
- cardctl shows at least recognizes the card as a Linksys Etherfast 
10/100 card
- cardinfo shows it as an NE2K compatible card.  
- Tried denying it various IRQs, but that didn't work
- Can't do anything with ifport except set it for auto-config
- For some reason, at a LAN that I set up at work, the network speeds 
from the DSL-connected router are excellent.  However, at 2 other LANs 
that I set up similar to the one at work, I get awful network speeds.  
The networks aren't anything fancy, just a few vanilla 10 Mb hubs 
connected together.

I've spent most of my time trying to unsuccessfully come up with a 
fresher tulip.o driver, but despite SCYLD's abundance of info, I'm 
running into snags with the compilation of the module.  Keep on getting a 
modversions.h not found.  When I place the modversions.h from my 
kernel-headers 2.2.17 in a place where the compilation of tulip.c can 
find it (/usr/include/linux/), I get a ton of misc. files not found 
that're from modversions.h.  I could hunt for those files and copy them 
over like I did with modversions.h, but I'm concerned that I might be 
wasting my time on this track if it turns out that the driver already 
present probably isn't the issue.  Like I said earlier, for some reason, 
the speeds are fine at work.

Any suggestions?

Thanks,

Steve