I am planning to migrate Oracle 10g (10.1) database from Unix (Sun Sparc-Solaris) to Oracle (10.2) on Linux running on Intel based processors.
I know two ways to do it.

1) Export and Import
2) Creating a bare minimum database on Linux and then using the transportable tablespaces.
Both of the above mentioned techniques may require a longer downtime or the two database would not be in sync. after migration.

I am trying to find a way to minimize the downtime. I would appreciate if I can analyze the different methods of doing it. Can someone point me to any technical documentation on this.