All power supplies in this country are 240v, you need to look at the wattage, there will be a label on the power supply that tells you this.
Because its AGP the best you can get is either a Nvidia 7600GT or a ATI 1950 Pro. I think the 1950 Pro might be the better card.
1950 pro needs 450 watts or above and the 7600GT needs the same.
Better to buy a branded power supply and if you get a high rated one then later on if you want you can use it your next PC and stick the old one back with the old graphics for resale or whatever.