Inspiron 530, video card replacement

Over the summer my neighbor asked if I could look into fixing their computer because it "suddenly stopped working."  Turns out, all she needs is a graphics card but the thing is I am almost clueless about replacing hardware on a computer. It's a refurbished Dell Inspiron 530 Tower, Vista 64 bit.  I believe, if memory serves from what another friend told me, the card I need will have to be 124 pin count.  I saw somewhere in the forums from google, someone was also looking to replace their graphics card for their Inspiron 530 tower - and someone posted a link from Dell for the card they needed, but that card is no longer in stock.  It sounded like based on what I saw in the conversation that you could get this card for under $50 (I have no idea what a good price is for parts - I'm more of  the person you come to if you need some help with viruses and speeding up your computer). Any help would be greatly appreciated.