http://www.shopping.hp.com/product/computers/desktops/p6150t_series/rts/3/computer_store/NP192AA%2523ABA

That is my computer. I get paid in two weeks, I am restricting my spending limit to 220$, could someone find me a nice graphics card? Also, I have a 300 watt power supply... so, I don't know what else to say. If I am not revealing enough information just ask. Find me a nice graphics card plz and thanks, I don't know how to do it mahself!!

I'm not Ex or Deathawk, but... I think you'll need a much bigger power supply to make use of a GPU for $220. Also, specify what you'll be using it for, so Ex can save you some money and not go over-the-top.

video games. Actually, I cannot run Demigod... I would like to run Demigod. If the power supply is a problem, is getting a new power supply a good idea? I know how to install one. (alot of people do i think?) Sorry, i am going off on a tangent... To answer your question I would like to be able to run Demigod smoothly, where as I cannot run it right now.

Oh, one more thing that might be helpful - monitor.

Im using my buddie's monitor. Its pretty decent, his computer is broke so w/e. 24" hd flatscreen

It is a fact that you will not be able to use any GPU worth buying at this point in time with that powersupply. However, if you want to replace the PSU and get a new GFX along with it, you can do that for 220$. Here are my picks:
XFX HD 4870 1GB
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150436
Antec 500w
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371007

Came out to $224.68 after tax and shipping to me here in NJ. I'm not sure if the 4.68$ is that big of a deal, if it is let me know. Depending on where you live the tax might be less.
Oh and I believe the XFX is on sale, so if it goes off sale before you buy, let me know and I'll find you something else.

thanks a lot Excalibur