What size to design?

[aumz]

I am doing a website but was wondering do you still design for 800 x 600 or can you go for 1024 x 768

 

[aumz]

When viewd ay 1024 I get a big gap between the content an dthe menu system on the right. What is the most popular display size, the site is a personal site and will only be viewd by friends and family