Well, there are no hard and fast rules on this but our advice is to gauge your audience.
There are benefits in using the bigger screen resolution size. However, this is only a benefit if you are not making it more difficult for others to view your site how it should be seen.
Think about your home user clients and potential clients and ask yourself:
1. How many home users will I be attracting i.e. home users refresh their hardware less frequently and many have 800x600 screens.
2. Which demographic will most of my home users fit into i.e. affluent quick changing home technology users or late technology adopters?
If you are appealing to mainly business users you can be pretty confident in using 1024x766. A very high proportion of businesses would have upgraded their screens to the bigger resolution format.
The rule of thumb is - if the choice of resolution is going to adversely affect your web audience in any way, go 800x600. You can make this format really work for you if you try.
