T-SQL (SS2K8) :: Convert Value To Seconds?

I want to calculate total sum of column.

I have a table with many values of column:

declare @time table
(times nvarchar(255))
INSERT INTO @time (times)
Select ('05:01')
UNION ALL
Select ('00:01')
UNION ALL
Select ('170:01')
UNION ALL
Select ('2543:01')
Select * from @time

How can I get seconds value for every row?

05:01 - 301
00:01 - 1
170:01 - 10201

P.s. Finally I use - Select convert(char,dateadd(second,152581,60),108) as sumtime