I have had difficulty running sonic adventure on steam since I purchased it, but eventually I managed to find a work around. This post is to help anyone else having trouble, with the steam version of sonic adventure simply showing a black screen. Note this might not applly to your PC but could be useful anyway.
Run Asus Boot Setting from desktop, and click direct bios.
when you are in the bios press F7
Go to advanced
system agent configeration
IGPU to run sonic adventure on steam
PCEI to get back to normal
it is F10 to save and exit.
My normal resoultion is 1280 x 1024
Anyway hope this helps anyone else suffering from steam's black screen problem with sonic adventure.