Upgrade ATI Onboard X200 with PCIe X800 GTO - Surely an improvement??

I have a simple presario that I am reconfiguring to work with flight sim 2004; and am concentrating on the upgrade of the current onboard video (ATI Radeon X200 express) to a Sapphire ATI Radeon X800 GTO 256MB DDR3/256bit/12 pipes.I want to confirm my assumption that this will greatly improve the rendering of FS2004...my main reason for the upgrade is to run dual monior for a home system for SOHO/Video/images/surfing...but while I am at it I want to be able to use FS 2004 with decent frame rates.at least I will be able to move some of the video effort off of the main CPU and MB RAMI can get the card above for ~$135....the system is AMD 2.0GHz, on an MSI Socket 939 MB, with 1.254 GB RAMThanks for any feedback