Highest Quality low-profile/half-size cards

Hi!

I currently own a Dell inspiron 531S which, while a quality computer, doesnt exactly have the best video card. I am looking to upgrade my video card as best as I can but through research it appears that its going to be a little harder than i thought.
Basically I have a 250W power supply and a slim case so i need not only a power friendly card, but a half size one as well. I have no idea where to begin looking so this is where i look to you.
What is the best Graphics card I can find for my PC that won't require me to buy a new power supply, and is also half size? Its most likely assumed but it needs to be a PCIe card as well.

Thanks in advance

For about $50 you can get a low-profile 4650. For $100 or so you can get a low-profile 9600GT. The 4650 will definitely work with your power supply. I don't know about the 9600GT.

+ 1, Rewindlabs is correct, you need to provide screen res. and other PC specs too thanks! This will help us to help you better lol.

I would recommend the 4670 as well, except I don't think anyone makes a low-profile version. I think those slim Dell cases require low-profile cards, but I don't know for sure. Sparkle actually makes a 9800GT low-profile card, but I doubt you can power it.

EDIT: AKM880 obviously types faster than I do and beat me to all of the above info

I don't understand, the posts in the first link imply that you do need a low-profile card. The 3rd post in the 2nd link only says that they ran a 4670 off of a 250W PSU, which I do everyday. It doesn't say that they put one in a slim case.

Just odd since regular PCIe cards are 4.4" wide and that Dell slim case is 3.9".