Might take a look at the performance dashboard and or the dm views on missing indexes and indexes used.

Okay, I have been able to confirm that the domain\server$ accounts are related to Reporting Services and application pools. the is a good write up at sqlblogcasts.com/blogs/stevechowles/archive/2007/07/02/reporting-services-2005-for-the-dba-changing-application-pool-identity.aspx that...