Whats the best way to...

Clean up boarders & edges? I cut an image out but its hard to get clean up the image boarders to make it look real nice and smooth. Whats the best way to clean up these nasty boarders?

well, depends.

1) Filter>>Blur>>gaussian blur do that about 5 times, decreasing the amount you do it by each time then adjust the levels. Image>>Adjust>Levels until they come out smooth.
2) Ctrl-click the layer of the image. Select>>modify>>contract by 1 or 2. Select>>Inverse. Delete.

second way wont work if its really jaggy.

I have been using the "feather" effect to make an image lose its sharp edge, im not sure if this will give you the effect you want as it doesnt always work for me, usual depends on the background. But you might try selecting the image, apply a feather of 1, inverse selection and delete (image has to be on its own layer), hide the selction to see how it looks and if its still to jagged hit delete again, every time you hit delete it shrinks the edge a little. Let me know if this works.