GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER,GL11.GL_NEAREST); GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MAG_FILTER,GL11.GL_NEAREST);When you create your textures, which will use nearest-neighbor sampling instead of mipmapping or linear interpolation for sampling texels that don't line up perfectly with the screen. (so a pixel that's halfway between two texels will be the color of the one it is closest to)
If that doesn't clear up the lines, another option to try (possibly along with the previous one) would be to add 0.5/spriteHeight to your texture coordinates' Y value, and see if that doesn't help.
Failing that, the other solutions I know of involve using shaders, which it doesn't look like you're doing here. LWJGL has some documentation on using them (and VBO's, which are unrelated here but quite useful) on its wiki, which could help you get started.