Check if table exists SQL

you can do it like this:
SQL 2000 syntaxis

    IF EXISTS (SELECT 1 FROM sysobjects  WHERE xtype='u' AND name='CVG86_SPE') 
BEGIN
             INSERT INTO CarnetMaster.GlassLookupCapacitySpecs
    (ID, CODE, NVIC, RELEASE, DISCON, DRV, TORQUE, KW, BORESTROKE, VINNUMBER, WIDTH, WHEELBASE, SEATS, COMPRATIO, TOWCAP, STEER,
    TURNCIR, HEIGHT, LENGTH, VWIDTH, KERBWT, PAYLOAD, GCM, GVM)

    SELECT NEWID(), CODE, NVIC, RELEASE, DISCON, DRV, TORQUE, KW, [BORE-STROKE], [VIN NUMBER], WIDTH, WHEELBASE, SEA, [TS COMPRAT], [IO TOWC],
    [AP STE], [ER TURNC], [IR HEIG], [HT LENG], [TH VWID], [TH KERB], [WT PAYLO], [AD GCM], GV
    FROM CVG86_SPE 
END

SQL 2005 and later:

        IF EXISTS ( SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME = 'CVG86_SPE' )
BEGIN
INSERT INTO CarnetMaster.GlassLookupCapacitySpecs
        (ID, CODE, NVIC, RELEASE, DISCON, DRV, TORQUE, KW, BORESTROKE, VINNUMBER, WIDTH, WHEELBASE, SEATS, COMPRATIO, TOWCAP, STEER,
        TURNCIR, HEIGHT, LENGTH, VWIDTH, KERBWT, PAYLOAD, GCM, GVM)

        SELECT NEWID(), CODE, NVIC, RELEASE, DISCON, DRV, TORQUE, KW, [BORE-STROKE], [VIN NUMBER], WIDTH, WHEELBASE, SEA, [TS COMPRAT], [IO TOWC],
        [AP STE], [ER TURNC], [IR HEIG], [HT LENG], [TH VWID], [TH KERB], [WT PAYLO], [AD GCM], GV
        FROM CVG86_SPE
END

Another way to do the same in SQL Server is to use the OBJECT_ID() function:

IF OBJECT_ID('table name', 'U') IS NOT NULL BEGIN
  INSERT ...
  ...
END

The second parameter tells the function to search specifically for the table, not for an arbitrary object, like a stored procedure or a user-defined function.

If you are checking for the existence of a temporary table, use it like this:

IF OBJECT_ID('tempdb..#tmp table name') IS NOT NULL BEGIN
  INSERT ...
  ...
END

(Here the second parameter is unnecessary because from the name of the object it is clear that it can only be a table.)