...just to add, avoid resizing or scaling images too high in page layout apps...
...generally you will be ok if the image is around 110% to 120% bigger than actual size...
...any bigger, it is well worth resampling the image in photoshop, you will still lose quality but photoshop will do a better job, bicubic resampling is the one to go for. if you have photoshop cs then use bicubic smoother or bicubic sharper...
...if resampling a screenshot from your computer better results are achieved using nearest neighbour...
andrew