Hi there,
The problem might not be with your bios settings but with the added graphics card. I lifted this from the ga-ma785gm-us2h page: * For Windows® XP, please must install AMD Chipset driver version 8.51 or later.
** Please use ATI Hybrid CrossFireX certified VGA card (i.e., ATI Radeon HD 2400, 3400 series). I'm not sure if the HD 4650 card is compatable.
Just to run through the bios settings for you, make sure that you are editing the advanced bios settings (ctrl+shift) to get these up.
1. Set the Internal Graphics mode to UMA then set your memory buffer size, remember that this will use system memory. (as you haven't got crossfire enabled this should be easy but these settings can't be made if crossfire is enabled in the software).
2. Set surround view to disabled. (Surrend view enables multi monitor set-up)
3. Set init display first to OnChip/VGA.
I would suggest that you connect your monitor cable to the output on your motherboard rather than the graphics card.
Your other issue with booting from CD after updating bios, have you loaded Optimized Defaults? If yes, check your boot order settings in bios.