Assigning new auto increment value
You can use DBCC CHECKIDENT to reseed the IDENTITY column.

Here is a sample you can run:

SET NOCOUNT ON;
USE tempdb;
GO

CREATE TABLE dbo.foo(ID INT IDENTITY(1,1));
GO

INSERT dbo.foo DEFAULT VALUES;
GO 100

-- note: set it to ([the next value you want] - 1)
DBCC CHECKIDENT(N'dbo.foo', RESEED, 499);
GO

INSERT dbo.foo DEFAULT VALUES;
GO 3

SELECT ID FROM dbo.foo WHERE ID &gt;= 98;


Results:

98
99
100
500
501
502