Also I used, http://www.antec.outervision.com/PSUEngine to help calculate and with all the system spec plus the HD 4670 installed, this site show the wattage is 273w (with 30% capacitor aging and 100% system load).
I think it should work, but I would like some feedback.
Also is there a better brand you prefer for graphic card (nVidia, HIS,Asus, .etc)?
It will probably work, but as you stated it didn't work for some people.
Here's an alternative idea, but it's you who must ultimately decide if you want to take a chance and it breaks your budget a little bit. Get a HD 5670 512MB video card and underclock a little using AMD's CCC. It costs about $93 shipped and is estimated to consume about 5w - 6w more than the HD 4670. Underclocking will help reduce power consumption.
Here's a THG review which pits the HD 5670 against the older HD 4670. The HD 5670 simply crushes the HD 4670, at worst is only over 20% faster (COD: Modern Warfare2), at best it is about 75% - 80% faster (Fallout 3). Eyeballing the benchmarks, it seems the HD 5670 gives you around 40% more performance:
Actually I decided to stick with HD 4670. As much I can see the benefit of spending 20-30 dollar on the HD 5670 to receive a tremendous boost, I can not spend on it unfortunately because I am too desperate due to my budget.
Seems okay. The good new is that your PC doesn't really consume that much power under load so a 300w PSU seems to be fine. If had to guess based on current configuration I think peak power consumption under load will be about 160w - 170w
It is a widely known fact (by those people who knows a thing or two about power supplies) that Dell is conservative about the actual total power output of the PSUs that they use. They have been understating total wattage of their PSUs for the past several years at least.