Pixels on my pictures. Help!

[PixelKid]

So I traveld around the world from Nevada to Washington, Oregon, California, Hong Kong, Japan, Thailand, Singapore, Hawaii and more All the while taking pictures with my ist*DS (which i love!) and then i go to put the pictures on my computer and they ALL have HUGE UGLY pixels. I'm shooting with the standard stock pentax lens with 18-55 zoom or my Sigma (70-300)... I may be dumb but i think the pixels come from the fact that im using a 6 Megapixel camera and then putting the pictures on my 18 inch laptop and the computer is trying to squish all that info into a smaller space and there's too much info to do that? i dont know! I just purchased Photo Explosion Delux to start editing some of my photos.. SO my question Does anybody know how to help me get these photos clear? =\ please help!

Check my gallery for examples