hey ppl I jst plaid the DOOM3 demo and found it quite same to the demo of Half-Life2. The story line of the games is quite the same. which one is better is really hard 2 tell and graphics quality of the games was superb and made me go mad. I plaid Doom3 demo in ultra quality on freind's pc having Geforce 6800nU of MSI with all its pixel and vertex shaders enabled. half-life i plaid on my home system having Geforce fx 5700 Ultra.