Short and simple answer though, is no. The old Pentium D series is not suitable for the latest generation of graphics cards. The new nVidia GTX 4xx series, and ATI 5xxx series cards would suffer fairly dramatic performance loss.
If you're looking for a graphics upgrade, you might provide more information about what games you want to play, what resolution you monitor handles, etc. Folks can suggest what works with your system. Otherwise, it's probably time for a system upgrade if you want to do serious PC gaming.
At a lower resolution like 1400x900 you certainly do not need anything like the GTX 470. It would be overkill for your needs (and therefore a waste of money). With your resolution, you could play those games with an ATI 5750 or ATI 5770 and do pretty darn well. Not to mention it would cost about half (or less) what the GTX 470 does.
Getting anything faster than an ATI 5770 is probably a waste considering your processor.
Make sure your processor has a PCI-E 16x expansion slot. And also, you'll probably want to look at the specs on the Power Supply in your computer to make sure it's up to snuff as well. If you're not sure, take the side panel off your PC. There's usually a sticker/label on the power supply itself that gives a brand, model number, and important details (max watt output, Amps on the +12v rail).
A 550W power supply should be fine for an ATI 5770, so long as it has a decent 12V rail on it. You'll also want to see if your power supply has a PCI-E 6pin power connector on it. If it's an older PSU, it probably won't have one. Sometimes video cards will come with an adapter that lets you convert a 4-pin Molex connector into the 6-pin PCI-E connector you'll need.
Unless you plan a monitor upgrade, the ATI 5770 is more than you need for playing games at 1440x900.
What motherboard do you have? If you have ~$300 to spend on a GPU, I'd spend ~$150-200 on a GPU and $150-100 on a new CPU. There are a number of C2D chips that might fit in your motherboard that will be much faster then what you have now. If you need to you could get a $100 GTS250 or 5750, and spend the other $200 on a new mobo and CPU. And you'd still be better off then with that P4D and GTX470.