everywere apears to be very limited in 478 boads(for good reason lol).
but heres a MSI VIA AGP 8x http://www.ewiz.com/detail.php?name=MB-PM8M-V
EDIT: i havnt, but you can also try searching around at for example:
EDIT: and remember, whenever you do get it setup, remember to go into BIOS settings and Disable the Onboard Video befor installing your Graphics card. (or you can install your GFX card from the start, and on First boot, go into BIOS and Disable Onboard Graphics Display adapter).
It may have an option to enable or disable onboard display adapter
or it may just have a option to switch primary display from Onboard/to AGP.
the majority of MicroATX motherboad come with Onboard display, and if you need a MicroATX board, there may be no other option.