Burnout is a rather unrealistic, fun, arcadey racing game isnt it? If so, you may want to check out the latest offerings from the NFS series. Need For Speed Underground 1 & 2 and Need For Speed Most Wanted may be your cup of tea. Demo's should be available for all 3 and they are all on both PC and XBox I believe (PC guarunteed).
Warhammer 40k: Dawn of War is the best RTS in the past 2 years in my opinion. Winter Assault is a decent expansion although I hear there are some balance issues in multiplayer. You can buy both the game and expansion in 1 package for a reasonable price and it is, in my opinion, worth the money.