Gm2 has a point with looking at Ebay, who knows what you might find there and dear old Gazz already did some research for ya
I don't agree that you'd have to stay away from the 1650 series, it's a great series that shouldn't be confused with the "normal" 1600 series which indeed underperformed. I was just hoping to find a 1900/1950 gt card for a good price somewhere, they can be oc éd to 1950 pro standards at the blink of an eye and that would make it an excellent card.
I looked around the US Ebay page and came across
this refurbished 7900GS. It's 55 dollars now, so if you bid a bit more you'd probably get it. Good card with some oc potential and with your processor being a 4200+, 1.5 gig and a seagate you probably wont run into any big bottlenecks and get to max out performance on this budget.