In order to fully use LinqToSql in an ASP.net 3.5 application, it is necessary to create DataContext classes (which is usually done using the designer in VS 2008). From the
I'd been wrangling over the same question whilst retro fitting LINQ to SQL over a legacy DB. Our database is a bit of a whopper (150 tables) and after some thought and experimentation I elected to use multiple DataContexts. Whether this is considered an anti-pattern remains to be seen, but for now it makes life manageable.