broke sql server...please help

so i installed sql server and i was using it within enterprise manager. Then it broke when i started trying to make my web application connect to my database. So my connection string was:

server=(local);database=capacity;User ID=dbo;trusted_connection=False

i got this error: Login failed for user 'dbo'. Reason: Not associated with a trusted SQL Server connection.

so i tried messing around with the string and found something online that said i should right click the server (local) and go to the security settings and change it to mixed mode, sql server authentication AND windows authentication. Before it was just windows authentication. So i did that...and now i get this error when i try to open up my server in enterprise manager:

A connection could not be established to (local)
Reason: Login failed for user 'samr'. Reason Not associated with a trusted SQL Server Connection..

Please verify SQL Server is running (which it is) and check your SQL server registration properties by right clicking on the local node and try again.

i can right click on it, but whenever i do anything (go to properties, click the '+' icon) i get this message:

Connection failed. Check sql server registration properties.

please help...

should i delete the registration and just start over...?

why couldnt i connect into sql server...?Take a look @.INF: Windows Authentication is the Default Security Mode After a SQL Server 2000 Typical Installation