Mysql 4.1 vs Mysql 5 Using All MyIsam

I have a one dedicated server for my 1 site. I want to seperate mysql server to an another box (Debial all). I m planning to to continue to use Mysql 4.1 but I am not sure? Is there any advantage of Mysql 5 versus Mysql 4.1 compared about Myisam performance and UTF_8 properties?

Best Regards
Supper