Would I be safe in assuming that the standard resolution for web users is 1024x768? The reason I ask is because I'm developing the web site for my school, except they've already gone and paid for a "professional" design and now I have to use that. The header image is 997px wide and it has writing which would get messed up if I reduced it although with a bit of playing around and yeah, I reckon I could get it to fit in 800x600 but I'm just asking.

What are the opinions of all you pros out there for a poor little beginner like me?