stuck with an agp 4x

[littlenicky]

is there any way that i can change my agp 4x into a 8x... and if i cant what is the best 4x that i can get

 

[[tab]]

8x is backwards compatible isn't it?

 

[littlenicky]

and also is there a 128 ddr with 4x

 

[mrjack]

I have an AGP4X motherboard and my AGP8X GeForce 4 MX440 works fine.