bad performance using ndis

hi,
I have R40 and try to get Intel 2100 wlan work.
I download new driver from
http://www-306.ibm.com/pc/support/site.wss/document.do?lndocid=TPAD-MATRIX
basicly,wlan works, but performance is bad:

64 bytes from 192.168.1.6: icmp_seq=92 ttl=64 time=6.718 ms
64 bytes from 192.168.1.6: icmp_seq=88 ttl=64 time=4267.039 ms (DUP!)
64 bytes from 192.168.1.6: icmp_seq=91 ttl=64 time=1544.590 ms (DUP!)
64 bytes from 192.168.1.6: icmp_seq=89 ttl=64 time=3765.145 ms (DUP!)
64 bytes from 192.168.1.6: icmp_seq=87 ttl=64 time=5986.673 ms (DUP!)
64 bytes from 192.168.1.6: icmp_seq=93 ttl=64 time=1.980 ms
64 bytes from 192.168.1.6: icmp_seq=94 ttl=64 time=6.855 ms
64 bytes from 192.168.1.6: icmp_seq=95 ttl=64 time=6.870 ms
64 bytes from 192.168.1.6: icmp_seq=96 ttl=64 time=7.209 ms
64 bytes from 192.168.1.6: icmp_seq=97 ttl=64 time=2.118 ms
64 bytes from 192.168.1.6: icmp_seq=98 ttl=64 time=2.929 ms
64 bytes from 192.168.1.6: icmp_seq=96 ttl=64 time=2223.507 ms (DUP!)
^C
--- 192.168.1.6 ping statistics ---
99 packets transmitted, 99 packets received, +104 duplicates, 0% packet loss
round-trip min/avg/max/stddev = 1.896/1928.298/10524.836/2269.834 ms

under XP, wlan works fine.

my CURRENT is very recent:
%uname -a
FreeBSD tp.gddsn.org.cn 5.2-CURRENT FreeBSD 5.2-CURRENT #5: Wed Jan 14
08:47:35 CST 2004 hwh_at_tp.gddsn.org.cn:/usr/obj/usr/src/sys/IBM01 i386


any suggestion?

--hwh