upgrade onboard gfx on vectra d5736 ..help!

Archived from groups: comp.sys.hp.hardware (More info?)

ok,my brother has this vectra d5736/PII 300 with 2mb cirrus logic onboard.He
has changed to standard vga, powered down and installed an 8 meg pci sis
6326 vga card.He powers up and the sis drivers seem to install ok.but when
he reboots after this the machine restarts and seems to post ok but
eventually stalls at a black screen with a blinking cursor. The system seems
to be frozen as he has to switch it off/on at the wall to get it to power
up again.
Do we need to change a setting in the bios? ,maybe to disable the onboard
gfx and what is the keypress to bring up the
vectra bios..He lives 4000 miles from me so i am trying to help him by phone
so the details may be a little vague.
Any info or links appreciated.
thanks.
steven.