Yes your mobo has PCIE1.0 slot and that supports HD4770. However check your Power supply. BTW which brand it is?
i dont know anything abt g c but my config said that its 100-127v ~/8a , 200-260 v ~ /4a 50 /60 hz
Either way, ill get a good quality power supply like an 450w - 600w good high brand PSU like Rosewell, Corsair, Antec, etc
One thing you have to look for is the Amps on the 12v rail. it doesnt matter if its 700 watts but only gives 19 amps on the 12v, useless. But on the other hand if its like a corasir tx 450 and gives 30 somewaht amps on the 12v rail, then itll give closer to its max power and also give sufficient power to your GPU or whatever.
I suggest a 450w Corsair or a antec 500watt one. Both are about $60? but can run any single card config (well.... offcorse not insane overclocked stuff)
Your PSU doesn't seems good enough for that card.
If you only want to add HD4770 then a Corsair CX400 will be plenty.
and what will its price in India< Mumbai >?
Around Rs3000.I highly recommend Corsair CX400. But if budget is a problem and you can't afford that PSU at the moment then I would suggest Gigabyte Superb 460W which costs Rs2200.