Well if you are planning to spend less than 200$ I doubt that the power supply may need an upgrade plus the new GPU will warn you if it isn't recieving sufficient wattage, then you can go out and buy a 500w - 600w for 40$ish.
Anyways if you want Nvidia look no further than the GTS 250... amazing card for the price and you can get it for about 95$ - 130$ right now from most canadian retailers.
If you REALLY care about Direct X 11 for the future... then turn to ATi because Nvidia doesnt have a mid end Direct X 11 card. (However you won't be able to turn on most DX 11 settings without mega lag on a mid card anyways so that's useless imo)
I also took the decency of comparing the cards technincal specs http://www.gpureview.com/show_cards....=606&card2=513
and it turns out that the GTS 250 will be about 2.5x - 3x (more likely 3x) better than your current card.
EDIT: Also try to find a Canada Computers... they are the best Canadian Computer retailer IMO and Tiger Direct is nice if you dont mind buying online.
Hm, he might try to update his GFXcard, but ultimately it will just bottleneck on his CPU.