Letterhead: Importing Pics to be placed as Header & Footer

[MissOffice]

Hi All..

- I want to make a Letterhead
- I have two images already made to be used as Header & footer
- When i import those images as art work into header or footer, the quality drops and the colors change, when printed fonts are not sharp.
- I do not want to use word to create the same thing because the graphic designer did a great job, i want to use pdf/tiff/jpg files he provided me.

--------Question:
How can i import/use the existing images i have, to build a letterhead in word(off course useable after just to add body text to the fixed page layout.)

Thanks.