forcing PC gamers to upgrade every 18 months! I bought my PC 3 years ago, and all I have done is take the ram up. I have the same dual core CPU and the same video card. I have been able to play everything from Oblivion to STALKER to Crysis to Empire Total War to Bioshock to Far Cry 2, etc on it.
The main reason is that PC hardware became much better (in relevance) and much cheaper in recent years and not because PC games don't push the envelope anymore (although exclusives are very few and far between).
Crysis most definitely pushes it. And especially games like Empire Total War - can you honestly say that your system deals with the game when you have 8 armies with thousands of troops running about?
And most other multiplatform games can be cranked very high to bring your system to its knees.