T-SQL (SS2K8) :: Assign Next Available Column Values?

find below object and data:

create table #StuDetails(City varchar(25),StuStatus varchar(25), currentValue int,Week1 int,week2 int,week3 int,week4 int)
insert into #StuDetails values('A','new',13,10,0,0,12)
insert into #StuDetails values('B','Old',10,10,41,0,12)
insert into #StuDetails values('C','Fail',10,9,0,0,5)
select * from #StuDetails

Output of above is display as:

CityStuStatuscurrentValueWeek1week2week3week4
Anew 13 10 0 0 12
BOld 10 10 41 0 12
CFail 10 9 0 0 5

Now for columns Week1 to week3 if value is 0 then i want to display by searching next week value, if it is also 0 then go for next week and if value found there then display instead of zero. so my output would be as below instead of above.

CityStuStatuscurrentValueWeek1week2week3week4
Anew 13 10 12 12 12
BOld 10 10 41 12 12
CFail 10 9 5 5 5