To center the page
padding:0; margin:0 auto;text-align: center;
And the menu seems to look better when the 'spaces' are replaced with htmlentities for the 'non-breaking-space' which is "ampersand"nbsp"semi-colon".
Hopefully that will display correctly on the forum to show you what the html-entity for a "non-breaking space" should be. If not, google it.
So, instead of the two words "guided holidays", place a non-breaking space between them ("guided holidays") in your source code.
The nbsp's are also needed in the top nav UL/LI's as well.
This may not be the most elegant solution, but it will help straighten things out until you wander over to http://csspplay.co.uk and check out a new menu for the page. Seems the one you are using at present is not happy with IE6. Stu at cssplay has several horizontal UL menus that would likely fix the problem better than simply adding the nbsp's.
Hope this helps.