Lock timeout detection in postgres 7.3.1

Hi
I have recently migrated my database from MS Sql
Server to postgresql 7.3.1. In MS SQL SERVER, it is
very easy to set the lock time equals to zero on ROW
LEVEL. So that if some other user try to access the
same data, he/she will get the error immediately. I
have tried to run the same code through VB 6.0
(windows) using pgsql as database on RED HAT LINUX
8.0, the only problem i am facing is when ever a user
try to access a pre LOCKED ROW, the program goes into
halt until the first user executes ROLLBACK or COMMIT.

Is there any way to set the LOCK TIME equals to ZERO
in postgresql 7.3.1?

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