SQL Server CE is EOL. You can use SQL Server CE 2005 (v3.1) and upgrade the existing database:
http://www.microsoft.com/en-us/download/details.aspx?id=17439
BTW: you can also use SQL Server CE 2.0 assemblies with newer Compact Framework versions. It will not only run with CF 1.0 but also with 2.0 and 3.5