(first, sorry if this is in the wrong forum!)

I bought an Epson v500 almost two years ago because I wanted to have more control over how my negatives came out by scanning them myself. I use the Epson Scan software.

I've always used it on Professional setting at 6400dpi (I know that's unnecessarily high), with the Thumbnail box checked, and with automatic exposure adjustment. I am somewhat satisfied with these results but I always noticed that there was a lot more grain than what I see in other peoples' pictures (even people with the exact same camera/film/scanner, such as this picture: http://www.flickr.com/photos/sealegs...ts/4946605824/). So recently I finally got fed up with what I perceieved as an unusual amount of grain so I started experiementing with different settings on my camera. Lo and behold, I found out what a different experience it is when you DON'T check the Thumbnail. Mostly it is a lot more work, but I noticed that the grain is a lot finer and the picture's texture is just smoother overall.
With thumbnail checked: http://i46.tinypic.com/mimp1.jpg
Without thumbnail checked: http://i47.tinypic.com/14436l0.jpg

So, at first I got excited, but there was another problem - the colors are way off, as you can see. I know the process should be: select inside the picture and press the auto exposure, and then increase the selection if you want to get the black borders (which I do). But I always end up with bad colors, no matter what.
With thumbnail: http://i49.tinypic.com/2l9ii4p.jpg
With thumbnail (post-processed in Lightroom): http://i45.tinypic.com/11t1pg2.jpg
Without thumbnail: http://i50.tinypic.com/2yn5xna.jpg
Without thumbnail (post-processed in Lightroom): http://i45.tinypic.com/ivbneb.jpg

As you can see, even if a post-process the crap out of the "without thumbnail" image, it still doesn't look quite right, color-wise.

So, my question is, what is your procedure for scanning? Any advice you could offer I would be really grateful for, I am very lost and discouraged about scanning my own negatives... it seems that no matter what I do, I can't get them to both have less grain and correct colors.