I have been trying to learn SQL 2005 from like a month or two and i think I have done a good job. Now I was about to try some security stuff in it but I saw that SQL 2008 is in market. Can any body suggest me that what is the difference between the two and can I switch to SQL 2008? What ever I learned in SQL 2005 will I be the same in 2008. And for trying it twice, where can I download express edition of SQL 2008? What's the difference between the original and express edition?