Processor really decides gaming performane in modern Games ?

[sumirandhamaskar]

i jst bought a hd 6870 gt a 4gb ram & want 2 knw that "Processor really decides gaming performane in modern Games ?"
OR should i buy any quad core processor for that matter ??? { i have a 20'' 1600x900 screen}

 

[sumirandhamaskar]

so with my upgraded spec-
amd phenom II 960
hd 6870
20" 1600x900 screen
4gb ram
how many fps would i get in most mosern games ?

 

[sumirandhamaskar]

3O+ AT ULTRA SETTING ??? IN BF3 GTA 4 ASSASSINATION CREED ???