sql server install - service account permissions

when i install sql server 2005, is there an problem with setting up the sql service account as a local administrator on the server? the notes suggest it may casue unwanted behaviour (or is this only related to side-by-side installations with previous versions?) can install sql server 2005 and add run the sql server and sql server agent services under the same account - and can i add this account to the local administrator group on the sql server?