Just to bring closure to this thread...
I got my G74SX back from service. Instead of pulling out the eeprom and burning a new bios, I got a new motherboard completely. Guess it's faster this way.
Well, it booted to windows all right, but it came back crippled. No 3D and no backlight on keyboard. Took me something like 6 hours of fiddling to get the correct version of the NVidia drivers for the 3D part as the latest ones from NVidia bugged my laptop and a couple of hours to get the keyboard backlight to work again (used Chastity's method).
Not impressed by the intimidation attempts from the RMA phone clerk - but there was no charge in the end - and not impressed by the quality control of the service techs who send back a crippled laptop.
The storm seems passed. Back to fighting with my awsome laptop.