Moving SBS2003 Server from one machine to another

Hello

I work on small company which has a server with
Microsoft SBS server 2003 Premium installed on it..It has the following roles:

1. Active Directory
2. Ms Exchange 2003
3. ISA Server 2003
4. MS Sql Server 2003

It is currently serving 15 Windows XP clients.
Because this machine seems to have some hardware problems i’m planning to change it with a new HP Server.
I wanted to ask which is the safest way to totally remove the old server and move all its services to the new one without any impact to the clients.I read about moving FSMO roles but is that enough?

thank you!