Safari vs Explorer problems…

Hi folks…
So I build my site on a Mac running Tiger. Lovely.
Initially I had lots of problems as this is my first stab at CSS. The site is used primarily as an on-line portfolio diary, really simple, nothing difficult. Anyway, it looks great on the Mac but when viewed on a PC running Internet Explorer I have this huge gap at the top of the page. This initially was coming out red but I managed to tweak the colour, but I don’t know which bit of my CSS is doing this? Its a pretty major issue in terms of look, but Im sure its somethign quite simple in CSS. Anyone any ideas or has any of you come across this issue? http://www.azurestudio.co.uk
Many thanks…