i had a buddy who had a 1.2 Athlon, 384MB of PC100 SDRAM, and a GeForce 2 MX200 and he could run HL2...Believe it or not.
Ahh, yea i beleive you. but thats when you put in the 'Directx Level 7' command. and run it on low. so it looks like shit with prolly 30fps and lower. so for single player mode, its practially uselss because theres no special effect that HL2 is famouse for.
i tested HL2 ona 9100 IGP ati, hardware DX 8.1, and by using the DX 7 command i could doubled the fps.
Note) on DX 9 hardware like, 6600gt. using the DX lowerlevel command didnt benefit at all, with very low fps increase.. while still a huge decears in quality.