When I look at a picture in my windows picture folder it says it's 2 megs for example. When I open that same picture in CS3 it is like 14 megs. What am I doing wrong ? Why is the file size so much bigger in PS ?
There's file size and there's image size, and essentially never the twain shall meet.
File size is just that: The size of the file. A JPEG will be smaller than a TIFF or a PSD because it stores the image data differently.
Image size is what you get when you take all the pixels in the image, multiply them by the bit depth of the image, and multiply that by the number of channels in the image. It represents the actual amount of image data the file contains, as opposed to the file itself.
To put it another way: You know those vacuum storage bags from the TV infomercials? You stuff your sweaters or pillows in the bag, hook them up to your vacuum cleaner, and bango—teeny little vacuum packed object?
Same idea here. The file size is the size of the bag once you've sucked all the air out with the vacuum. The image size is what you put in the bag to begin with, and will have back again once you break the seal.
