256mb apature size is usually too much (set at half your system ram is usually best) you set that in the bios. It should run in 2x just fine, but some motherboards can have problems with some cards sometimes have problems.
To prove that the geforce 4 does support 2x agp, here's a short spec list of the leadtek winfast A250 (gf4 4600):
Hardware Features
Nvidia nfiniteFX⢠II Engine
Dual Programmable Vertex Shaders
Advanced Programmable Pixel Shaders
Nvidia Accuview⢠Antialiasing
Nvidia latest nView technology
3D Textures
Shadow Buffers
8 texels per clock cycle
Dual cube environment mapping
128MB high-speed DDR RAM memory
High-Definition video Processor (HDVP)
AGP 4X/2X and AGP Texturing Support
just about all nvidia cards from any brand are pretty much the same
So it does support it, their must of been something wrong with your hardware/software for it not to of worked. Besides, 4x agp doesn't make a large difference yet anyway
