Here are links to my troubleshooting articles helping you find out how and why SQL Server isn't performing and what you can do about it. If you're really struggling, drop us a line and we can help!
Troubleshooting with wait statistics
A guide on using the sys.dm_os_wait_stats and sys.dm_os_waiting_tasks Dynamic Management Views within SQL Server.
Monitoring SQL Server with Dynamic Management Views
First post in a series on how to build a server monitoring query using DMV's.