not able to connect to sqlserver

[yoshitha]

Hi
below is the connection string
<appSettings>
<add key="connectionstring"
value="server=localhost;uid=sa;pwd=thanks;database=schoolDb"/>

</appSettings>

when i use loclhost or my system ip address to connect ot database in my
system then i'm getting the follwoing error


An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred
in system.data.dll

and i kept my database in other system and while giving that system name or
ip address also i'm geting the same error.

but when i use my system name instead of localhost or ip address of my
system then i'm able to connect to database.

my system config
Microsoft Windows XP
Professional
version 2002
Service Pack 2, v.2096

can anybosy tell me why i'm getting this error?
thanx
Yoshitha