True64 vs Windows 2002 vs linux

I have a client that has 9.1 on unix True64.
He will migrate to 9.2 and buy a different server.

He want to use a different os, he's asking me advice on the os choice.
True64 vs Windows 2002?

Well im thinking to swicht from True64 to linux. Cuse they know well the unix environnement.

Price is also a factor, that is why im thinking linux. What about oracle license, are they cheaper on linux compared to windows 2000 plateform?

Anyone has a opinion and facts on os choice, considering price and availybility as well a easy maintenance?

If they already know Unix, Linux is the better choice over Windoz, IMHO. There used to be a conversion charge when you changed platforms, but I'm not sure Oracle still does that. As for new licenses, it is always best to ask your Oracle Sales Weenie as they know your environment better.