Hi Guys
Thanks for the help, i've managed to fix the problem.
MadHuriMN - Thanks for the help but I'm a web developer and use CSS and need colours sizes and styles to be allowed.
Dan - your link helped me:
If you change the text size settings in Internet Explorer 6 to something other than the default (medium) and then view an e-mail message that uses Hypertext Markup Language (HTML) format in Outlook 2000, Internet Explorer reverts to its default text settings the next time you start Internet Explorer.
TO FIX THIS
To resolve this issue if you are using Internet Mail Only mode in Outlook:
In Outlook 2000, click Options on the Tools menu, and then click the Mail Format tab.
Under Stationery and Fonts, click Fonts, and then click International Fonts.
Select the font size that you want to use in Internet Explorer, click Set as Default, and then click OK until you can quit the program. The font size should no longer revert to the former default (medium) in Internet Explorer.