Failover cluster : SQL 2000 to SQL 2005 upgrade

Hi All,
I'm not a good in DB and have come across a recommendation from vendor that
database server need to be upgraded to SQL 2005.
Previously it was pretty easy as I just uninstalled and installed latest SQL
server. But now, the database has been moved to a Failover Cluster which
bothers me as I've never upgraded a cluster server to it's latest SQL
services.

Could someone recommend me a suitable "step-by-step" guide to same?
I don't want to rebuild cluster rather I’ll prefer taking time and upgrading
it.


Thanks & Regrads,
Ashutosh