Saving as web page in Microsoft word

Solution 1:

Eww... please don't use Word to create web pages. It generates a soup of MS-specific HTML and CSS, which is horrible for browsers, and completely unmaintainable except through Word.

If you want to be designing web pages visually I recommend a tool such as Microsoft Expression Web 3.

Solution 2:

Word assumes a fixed page width. That's why you can tell word how big a page should be. The web however, doesn't (or at least shouldn't) make any such assumptions. When writing HTML, either manually or using Word, you have no way of knowing how large the broser window will be when the HTML is rendered again.

If you want a fixed layout that looks exactly as it looked in Word, convert your document to PDF and offer that for download.