I went for the export/import-option. I hated it. Why? Because there was a difference with the National Character Set. You can only choose UTF8 and that UTF16etcetc in 9i and the 8i National Char. Set was different.
The import stated that there could be a character conversion... could be...? It didn't report that conversion actually took place, so I'm a bit worried. But everything went okay and the applications worked fine.

The only strange thing was the listener. It wasn't present in W2K after the complete installation and configuration. I had to start it manually with TSNLSNR.EXE in the BIN-dir. I'll do some extra reading on the subject.

Oracle9i is very coool. Everything worked (e-mail via OEM, etc)