Click on start - select all programs and then windows update should be near the top this will give you all the updates required for your version of windows.
Alternatively click on this link if it's too tricky to google what you want
Don't do what I did recently. I downloaded the latest Beta version of IE and when I found some glitches tried to revert back to the previous IE. But I kept getting an error message saying you cannot revert back to a previous copy. I even tried to revert back by doing a system restore without success. Version 7 should be OK to move forward to though.