NIC Sleeps after some idle time

My home machine has two NICs.  Eth0 has ip address via DHCP (ADSL). Eth1 has static ip.  Everything works, except that eth0 seems to "fall a sleep" once in a while.  Once it is in this mode, I will not be able to ping, telnet, ...etc from outside, my internal network (via eth1) has never had any problem
getting out. Once eth0 falls asleep I would have to try later and it will somehow wake up by itself (after about 10-30 minutes).  APM is turned off on the BIOS (I heard claims it might be the problem, but I question why eth1 never falls asleep)
I also noticed that if I have my wife ping an outside site from my home machine, eth0 will come back alive right away.  So my only solution now is this is to have the
home machine ping an external site (ex. www.yahoo.com)
every 1 minute.  With the ping on, I can alawys get to
my home machine from work.  I have few peopel on
the web that have the same problem and none could
figure out what the story is.  BTW, under NT, the problem goes away.
Thanks