I need help figuring out which video card I need!

i have a HP Pavilion a6519fh Desktop PC with OS windows vista (dont know what bit) and my video card kinda sucks, and i bought the game GTA IV, and it says that i need to upgrade my video card, and thats the trouble that im having. i have read info about needing to try and find what motherboard name i have. here it is:

•Manufacturer: Asus
•Motherboard Name: IPIBL-LB
•HP/Compaq motherboard name: Benicia-GL8E

the price range of a video card that plays GTA IV fairly well, is no more than $100 if possible.
 
yes, that is my motherboard.

Here are more specs:

Product number
KT373AA

Introduction date
23-May-2008

Country/region sold in:
•United States

Hardware
Base processor
Pentium E2180 (C) 2.0 GHz
•800 MHz front side bus
•Socket 775
Chipset
Intel G33 Express
 
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