i guess, but since i know nothing about q4 i can't say whether it would do much good or not. for example ET relies a lot more on your cpu, when i overclocked my vga i got 5-10fps more (constant), when i overclocked my cpu i could maintain 100fps constant, whereas i usually play at 76. check whether q4 relies more on vga or cpu
ouch :/ but don't overclock your vga without knowing whether it's gonna be effective or not, if it's not worth the risk just play with what you have ;x
HP shit thing