multiple indexes vs multi-column indexes

i've only adding an index list sql server 2005 got me thinking. inadequacy between formulating 1 index defining churned columns over carrying 1 index per buttress wish index.

are there certain reasons since should used over other?

for example

create nonclustered index ix_indexname tablename
(column1 asc, column2 asc, column3 asc)

versus

create nonclustered index ix_indexname1 tablename
(column1 asc)

create nonclustered index ix_indexname2 tablename
(column2 asc)

create nonclustered index ix_indexname3 tablename
(column3 asc)