hi,
i have installed sql-server 2000 on win-xp pc . but when i am using sql server it requires authentication from server ,but i do not have any server ,by this i am unable to use sql database in my vb application .is any method to use sqlserver 2000 without any server pc .

buddy,

You can install Sql Server edition in Windows XP.

So what you might have installed is the server edition.

Try to remember while installing you might have selected
windows authentication or mixed mode.
if mixed mode then it should have asked you for administrator password

generally sql server administrator id is "sa" and and try to remember what the password you kept.

this should work.
Thanks,
Chaitanya.