Hello, i am new here and i need help with my car pc project!

ok, my english is not so very good (school english ca. 30 jears past )

my problem is i have buy a Digitax 3G MDT /f at ebay with win ce 4.2 professional on it
now i want to make ce 5.0 on it but i don`t now how?

where can i become win ce 5 to download or buy?

please help!