The fastest way to improve database performance is to put the tempdb on a ram disk (free download at dataram.com). That works even if you have to reduce the ram available to the database itself. The tempdb is created from scratch every time you start up the SQL server (put the temp files in the root directory of the ram drive). I had a 4gb ram 2xopteron 2,2ghz hp dl385 g1 server with 6x72gb 15k u320 in a raid 10 running windows 2008 x64 an SQL server standard x64. I gave the SQL server 2,5gb ram and put the tempdb on a 512mb ramdrive leaving 1 gb for windows (+ pagefile). This performed very well for a 22gb database. in production I have more ram (25gb) but still take some from the SQL server and use it for a ramdrive. I strongly recommend using quest spotlight on SQL server for further optimization. I bought it before investing in new hardware but there is also a 30 day trial version.