Then just get a 5670. the 4870 is an older card.(right?)
But would get outdated faster.
i really want the 5670 since it has really low power consumption and it runs games greati'll probably stick with that and if it's underpowered i'll buy a 400watt PSU later when i get more cash
http://www.newegg.com/Product/Product.aspx?Item=N82E16817182021http://www.newegg.com/Product/Product.aspx?Item=N82E16814102871
Just make sure that your motherboard has a PCI-E slot, man.
is it possible the 5670 won't fit?