What are you comparing actually - screenshots, videos, actual gameplay played by you?
You never compare a console to a low end PC. Because consoles are sold at a loss. For example, PlayStation 3's initial production cost is estimated by iSuppli to have been US$805.85 for the 20 GB model and US$840.35 for the 60 GB model. However, they were priced at US$499 and US$599 respectively, meaning that units may have been sold at an estimated loss of $306 or $241 depending on model, They make profit by taking cuts from games. That is the reason why PC games are cheaper. So always compare a console to a high end PC.