I'd like to know if there is a difference between 2gb sd memory card and sd
lightning speed memory card same gb

I finally purchased a Canon S5 IS and chose it
over a Panasonic FZ18 because of lower noise and better image quality
in producing an 8x10.  I will have to forgo the wide angle on the lens.

Now I need to make a decision on weather to get the Lens Hood and
Filter

Has anyone here any experience with the larger SD cards. I bought a 4 gb
"SDHC" card and my Pentax uses it quite happily. However I cannot find a
card reader that can access the contents. They either freeze or tell me that
there is an i/o error.