> ... most of the time the thread ended with 'this is caused by a buggy nic
> driver' what's everyone using?

  I tested several different client NICs, using -current installs less than a
week old.  Only my Xircom gave the error:

tlp0 at cardbus0 dev 0 function 0: Xircom X3201-3 Ethernet, pass 0.3
ukphy0 at tlp0 phy 0: Generic IEEE 802.3u media interface


 These x86 3Com NICs were fine, with and without hardware checksums enabled:

ex0 at pci0 dev 13 function 0: 3Com 3c905C-TX 10/100 Ethernet with mngmt (rev. 0x78)
exphy0 at ex0 phy 24: 3Com internal media interface
ex1 at pci0 dev 16 function 0: 3Com 3c556 MiniPCI 10/100 Ethernet (rev. 0x10)
tqphy0 at ex1 phy 0: 78Q2120 10/100 media interface, rev. 11

 These sparc NICs were also fine:

le0 at ledma0 slot 5 offset 0x8c00000 level 6: address 08:00:20:90:75:de
hme0 at sbus0 slot 1 offset 0x8c00000 level 4 (ipl 7): Sun Happy Meal Ethernet (SUNW,qfe)
qsphy0 at hme0 phy 1: QS6612 10/100 media interface, rev. 1
hme4 at sbus0 slot 2 offset 0x8c00000 level 4 (ipl 7): Sun Happy Meal Ethernet (SUNW,qfe)
ukphy0 at hme4 phy 1: Generic IEEE 802.3u media interface

>> I get this from a NetBSD DHCP server so its not just Win2k being dense.

 My DHCP server is WinNT with an unknown card from Compaq.