Security Service Accounts

For both WSS and MOSS I like to use the least privileged account methodology for all my deployments. This is considered Microsoft best Practice.

Account	Usage
SP_Admin	SharePoint set up account, used to install SharePoint. Local administrator on web front end. DB Creator on SQL.
SP_Farm	SharePoint Farm service account. DB Creator and Security Admin on SQL. Also used as the Central Admin application pool identity.
SP_WssSearch	WSS search Account.
SP_MossSearch	MOSS Search service Account.
SP_Content	SharePoint Content Crawl Account.
SP_Profile	User profile import account.
SP_SSPAppPool	Application pool identity for Shared Services Provider
SP_PortalAppPool	Application pool identity for Portal web application.
SP_MyAppPool	Application pool identity for Mysites web application.
SP_Excel	Excel Services service account.
SP_SSO	Single Sign On service account.

Above is a general guide of what I use when deploying WSS and MOSS environments. Some of the above accounts are not needed for WSS.