Ad Blocking & Emails

Can anyone tell what free ad blocker i can use to stop the grey ad boxes and adverts that pop up. I have tried the Windows XP Firewall but this prevents me from downloading some of my websites.

I Have installed and using Incredimail instead of outlook express , does anyone know how i can change all my email folders(inbox, sent etc )back from the incredimail folders into the outlook express folders and then save them.

Is any way that i can do the same in outlook express as i can do in Incredimail(i.e Background,font type)