changing default email server

I was one of the lucky ones who got the Blaster Worm and it really did a number on my laptop. After several attempts with the reformatting CDs that came with the HP laptop I still had problems and HP gave me the steps to use the Blaster Removal Tool and patch. Problem is now I want to choose IncrediMail as my default mail server, but an error window comes up and says only Administrator and Power User can do it. Well, I am both and yet still can't make the changes

Any ideas

BTW I 'lost' scan disk and a photo program during all the 'repairing' would MS Win XP have a program so I could download scan disk again??? Defrag wouldn't work until I went to search and found it and created a shortut to the Desktop and then it ran.