What technical issues am I likely to encounter when migrating a database from SQL Server 2000 to SQL Server 2005? Are there any common problems I should be aware of?
Should i be worried about any T-SQL changes that may break when stored procs are executed against the newer version of the database?
What about DTS packages? Are there any migration issues there?
Generally speaking, migration should be fairly straight forwards.
You can set the database in SQL 2005 to run in compatibility mode for SQL 2000, but you shouldn't have a need for that.
One thing I would advise is to do a test migration first before doing it on production, just to try it out and have the opportunity to catch any issues. For example, check the performance within SQL 2005 - you may find that some queries may need to be tweaked if performance deteriorates. e.g. I've seen instances where to improve performance on SQL 2000, an index hint was required on the query. This had the opposite effect in SQL 2005 resulting in far worse performance, meaning the hints needed to be removed again (as is mostly the case, index hints shouldn't be needed)
Update 1:
Regarding DTS packages, I won't attempt to explain the options better than this MSDN article does, it's pretty comprehensive :)