First have a look at Microsoft Whitepaper that gives you an overview of the process. Make sure you get the SQL Server 2008 Upgrade Advisor. It will analyze databases and check for incompatibilities. It does not write any data to database you’re analyzing. I highly recommend it, if you’re making such a big jump as we did. Also, apply SP1 (currently the newest), and Windows updates.
The machine I’m working on is a 64bit machine with 16 GB RAM. Make sure you adjust the max memory taking up by SQL Server. By default, it will try to consume the max you have (the setting will be set at roughly 2 petabytes). To prevent OS starvation of memory, on a machine used for just SQL Server, allot 10-15% of memory to the OS. The rest will be for SQL Server. With 16GB, I set it to 13GB (13312 MB) of memory.
Also, I urge to change the compatibility level to SQL Server 2008 (100), that is of course, the Upgrade Adviser throws a lot of issues and you’re on a tight deadline. Certain features have been deprecated and removed. For example, this will no longer work on 2008 (order by [table alias].[column alias]):
select AreaID aid, ParentID, Name from Areas a order by a.aid
or this way of truncating will no longer work:
To avoid problems for future upgrades, it’s best to switch the compatibility to 2008.
Also, as an obvious reminder, keep a backup, especially if you’re going to do a detach/attach migration. Once you attach the 2000 db files to 2008, you can’t retach to 2000. I prefer a traditional .bak restore.
Lastly, I highly recommend this checklist when upgrading.