To Increase Scalability of the database in 2005

Hi,
Apart of the links suggested by Mohammed, I have few more for you
http://www.microsoft.com/technet/prodtechnol/sql/2000/plan/ssmsam.mspx
http://msdn2.microsoft.com/en-us/library/aa902665(SQL.80).aspx
http://www.sql-server-performance.com/articles/clustering/massive_scalability_p1.aspx
http://www.sql-server-performance.com/articles/per/ultimate_scalability_availability_p1.aspx

The above link should give you gist of what SQL Server 2005 can offer you to attain the scalability, but in the real terms it depends purely on your current system & application, not to mention about code used to access the database.
So when you talk about scalabiltiy then 'benchmarking' it is to define the business requirements, including functional, performance, with scalability and translate them into system specs. At the same time you need to generate a workload script, accounting for user load and transactions during busy times & quiet period on the databases.
You need this in order to stabilize the environment of and enable monitoring on monitored server, not simply documenting or defining benchmarking would do any better. For the best results you have to execute baseline test; benchmark tests scale up in phases and assess the results. If you are in doubt you could go through your Service Management team to get more information