Hello I got an ibm z60t with a "Broadcom NetXtreme Gigabit Ethernet" the driver of xp is called b57xp32.sys so i suppose is the same you are working on.
vesa works fine with the intel 915gm/gms it has. (really didn't try the native one, has the i810 driver support for this cards ? ) I can be a tester too if you need. (please tell me i will not need to return to vmware or qemu!! :-D ) thanks gabi
