If you are connected (using the instance name) you can also find it by query (SQl2000 and up):

set nocount on

go

DECLARE @SqlPort Nvarchar(10), @instance_name Nvarchar(30), @reg_key Nvarchar(500), @value_name Nvarchar(20)

if left(CAST(SERVERPROPERTY('ProductVersion')AS sysname),2)...

Less sophisticated but what also would work (ans also on sql 2000):

select col1, col2, col3, col4 from Mytable into #tmp_Mytable

group by col1, col2, col3, col4

truncate table Mytable

insert into Mytable select...