We have some servers with Windows 2003 and SQL Server 2005 and would like to upgrade them to Windows 2008 and SQL2008 because of the new cool features.
How can that be done? Anything in particular to think about?
If you haven't done this kind of thing before I can't possibly reinforce how important it is to perform a full lab of what you intend to do first, don't skip over the testing and verification step before doing it for real or you will more than likely run into very serious problems.
As for the upgrade itself you have two major upgrades here the OS and the Database server, so a number of questions need to be answered.
Does the server do anything other than serve the Databases? If so can you afford a downtime of up to the time it would take to do a fresh install of the OS / Databases? This would give you the best case scenario, as you would have no traces of the old OS / database server on it.
If you go this route you can upgrade the database by performing backups / restores which is covered well on the Internet already.
Once again don't neglect testing in a lab first!
There's a definite order to upgrading SQL and Windows on the same machine. Unfortunately my notes are at work and I'm at home. I'll post my notes here tomorrow when I'm back in the office.