a) your video card is not the issue. You don't need to have an i3 or i7 and still have a qaud you know
For intel there is the intel core duo Qxxxx series that are "quad" (i have been told not true quads however). There is also the amd route as well.
b)30 fps is considered ok. You want higher though.
FYI my pc:
Intel Q6600
some random asus mobo
xfx nvidia 9800gtx +
4gb of ddr2 ram
antec nine hundred case (don't go cheap on cases. A heavy case means less flimpsy side doors on them)
550W PSU? don't remember.
Cost me around 1000 back in march of 2008. More than likely would cost nothing now. It cannot play all modern games at max ( and still have 40+ fps). However 95% are playable at max.
The best part though? having word several spread sheets open 2 client of eve online on and Mozilla Firefox without breaking a sweat.
Anyways it is your pc make up your own mind. FYI get a new heatsink if you do buy intel. The push pin design of intel heat sink are the worst thing ever invented (not just mine but also some professional computer nerds opinion like my brother). They come undone sometimes when a pc is jolted (in a car for instance). Spend the 50 bucks and get a back plate and bolts kind of heat sink.