The Corsair 450VX offers 33A on the 12V rails. The Seasonic 430W only 30A. Both are quiet, according to reviews. You can read some user reviews at Newegg if you want.
With either of those two, you can upgrade to 9800GTX+ or HD 4850, but I wouldn't go any further. The CPU would limit a more powerful card anyway.
I don't like the prices, TBH. $60 for the Corsair and $70 for the Seasonic at Newegg (in the USA). For that money you might as well get the PC Power & Cooling 750W S75CFhttp://www.newegg.com/Product/Product.aspx?Item=N82E16817341011&Tpk=s75CF
That one would power even an HD 4870 X2 and a quad CPU. I have one and can guarantee it's silent. It might not fit in your old case though.
Edit: don't get the 8600GT, it's not a gaming card. I have one on my work PC and it's fine for Office and Visual Studio, but that's about it. The 9600GT is decent. The 9800GTX+ is much better, and the HD 4850 a little better still. The 9800GTX+ is pretty big, so measure how much room you have in the case if you want that one.