Question : MS SQL Server only using one core on a 4 core box

I have an instance of MS SQL Server 2005 Standard and it appears that the sqlserver process is only using 1 core (1 thread) of the 4 core processor.  This is begining to cause some performance issues on our application.  Is there a setting somewhere in SQL to adjust this or to force the sqlserver.exe process to use all cores?

Answer : MS SQL Server only using one core on a 4 core box

According to this: http://www.newegg.com/Product/ProductReview.aspx?Item=22-136-489&SortField=3&SummaryType=0&Pagesize=10&SelectedRating=-1&PurchaseMark=&VideoOnlyMark=False&VendorMark=&Page=1&Keywords=2008

Windows Server 2008 is not supported...doesnt really make sense to me though.