If like me, you are trying out the new stuff in SQL server 2008 you might need some data to work with. The standard Adventure Works sample databases for OLTP and data warehousing are not in the CTP nor is the the analysis services project. So you'll need to get them from Codeplex which not only has these but some useful discussions. You will also find a light weight version on here.
I would also add that if you pull down the the virtual hard disk with the latest CTP4 installed on you'll still need to add the samples afterwards. I have asked the team who runs connect for them to be included.
I have always used these samples for trying out anything new or to crack a particular problem as this can be shared with anyone else including Microsoft support. For those of you who are struggling with MDX , the industry standard language used to retrieve data and add calculations to a cube ,then this is essential. I have yet to see an example that can't be written into the adventure works cube and I have often found that recoding it from the project I am trying to implement shows that the problem can often be in the cube design. The sample are also good for testing security scenarios, which can often simply be " I can't connect to the live database so can I connect to Adventure Works".
So resist the temptation to delete the database from you dev and test machines and use them for R&D on Friday afternoons like I do.
try to tst with sample of 2008 sql