Use of Pivot

Hi I wants to explore Pivot cluse SQL 2005
I have a table
tbl1(
col 1 decimal,
col 2 decimal,
periodending datetime
)
O/P i wants in this format
period1 period2 period3
sum(col1) sum(col1) sum(col1)
sum(col2) sum(col2) sum(col2)
How can i achive this
my I/P will be
period1 = periodending between (date1) and (date2)
period2 = periodending between (date3) and (date4)
period3 = periodending > date(4)
Thanks

Implement through the case statement...