Are you seeing IO bottlenecks? (perfmon, physical disk:avg sec/read, physical disk:avg sec/write, physical disk:% idle time)
First things first, before you go looking for hardware. Fix the queries, fix the indexes. If you can tune the queries and create indexes that will support those queries you will see a much greater performance improvement than if you bought new hardware.
If you haven't a clue where to start, suggest to the boss that getting a consultant in (someone who specialised in performance tuning), is likely to get things fixed far quicker than you could, and you'll learn from them in the process.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
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