Task Manager's I/O number could be misleading without knowing how long the server has been running. What are the specs of SQL Server? Min/Max memory settings. What are the database sizes on the server? Just an I/O number doesn't give much to go on.
As for klnagent.exe, you might want to check your virus scan settings. If you have real-time scans on the database files, you could be begging for performance problems.
I suggest you look at running process explorer instead of Task Manager. You can get a great deal of information that Task Manager just doesn't have.
Download it from microsoft here:
http://download.sysinternals.com/Files/ProcessExplorer.zip
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When you realize you've dug yourself into a hole....Step 1...stop digging.