your processor is nto the issue its ram and video card a good 2 gb card pci express would be good ddr3 or better.
for your ram i went from 4 to ten and its a vast improvement just my 2 cents
dual core with 3 gb ram could be better
this is his pc http://www.newegg.com/Product/Product.aspx?Item=N82E16883109040
Graphics
GPU/VPU Type
NVIDIA GeForce 6150 SE
Graphics Interface
Integrated video
again dude run as administrator and check properties for your gta folder make sure its unchecked read only
it is only your tazer that wont work if u install it this way