When I started using Creighton's AA build, the lines between quads disappeared for me.  Maybe play around with antialiasing options?  See if that helps.

hey, i know this is an old thread, but fyi, in case it helps anyone...

for non-transparent textures you can usually fix this by offsetting uv in one pixel, so for example instead of using 0..511 on a 512x512 texture, use 1..510 (assuming you can live with the minor misalignment as a tradeoff).

transparent is harder - i was having a heck of a time trying to solve transparent fringes around quads (winxp, ati radeon x600), and what i finally tracked it down to was the mipmap settings on my card.  i have it set up to override application settings so aa is always on (necessary prior to current processing builds with the aa hint) and line-aa/texture-aa/mipmaps are all set to highest quality.  what it was doing was creating a "blur" in the alpha channel of the mipmaps, but i didn't want to turn it off because it does improve the quality.  so the fix?  buffer the texture image with extra transparent pixels, then offset uv accordingly.  for example, at highest setting i needed a full 16 pixel padding on a 512x512 texture before the blur went away completely.  then output vertices like (minx,miny,16,16) - (maxx,maxy,tex.width-16,tex.height-16), so you effectively have a 480x480 "usable" area of the texture. (or pad upwards into the next larger power-of-2 if you need all of the original texture - lots more wasted memory though)