Paul Raver :
That is tight budget since you might need a new PSU to go with a new card.
Should be a sticker on the back end of your rig that will tell you want PSU you have and how much watt.
He doesn't necessarily need a new power supply. Granted, if his power supply is of a crappy make/model, he might be interested in replacing it
regardless, but the beautiful thing here is that PC tech has grown more power efficient over recent years at the same time that it's grown more powerful. Apart from the chassis, a good power supply actually has the longest potential lifespan of any component in a new rig these days, remaining relevant for possibly two or three future builds.
So the long and the short of it is that the if the OP wishes to post more info about his power supply, we can certainly evaluate whether he should replace it. But in principle, unless the OP's power supply is total and utter crap, he should be ok. The 9500 GT, based on the old reviews I could dig up, was a very low-power card, lower than the 650 Ti Boost. The 650 Ti Boost is by no means
a great power hog, though. Max power draw looks to be 118 W.