Handling SQL server Connection and Program logic

Dear all,
Is anyone of you encounter 1500 webstation concurent access to the Microsoft SQL server for SELECT statement. Can microsoft sqlserver handle it wisely, because I'm looking to around 4000 webstation concurently access to the database in the future growth.
Secondly i wish the help from you all, it is a good practise that i should do all the logic in the database or let the logic to the asp.net program, here is the sql query i wrote,

DECLARE @msg varchar(255)
if (select overrideind from webstation where webstationid=3) = 'y'
begin
SET @msg = 'y'
PRINT @msg
Select ms.setid,ms.setseq,ms.itemid,ms.menuid,mi.filename,mi.url
from mediamenuset ms inner join mediaitem mi on ms.itemid = mi.itemid
where ms.menuid = (select menuid from webstation where webstationid=3)

END
ELSE
BEGIN
SET @msg = 'n'
PRINT @msg
select ms.setid,ms.setseq,ms.itemid,ms.menuid,mi.filename,mi.url
from mediamenuset ms inner join mediaitem mi on ms.itemid = mi.itemid
where ms.menuid = (select wgrp.menuid from webstation web inner join webstationgrp wgrp on web.gid = wgrp.gid where web.webstationid = 3)
END


but it is good i do it in the program and make a database connection to get the result. If i left it to the program so i need to execute 3 select statement, the programming logic will be in between each select statement, Before this 3 select statement checking i also have another 2 sql query executed, so totally will be 5. Because i think about 1500 concurent access to the database will it holding the connection too long. The Pro and Con really make me sick, if not the database then the webserver which will handle the logic in asp.net also will be bulky.
Should I consider the connection problem or the server processing problem or the database processing in this situation. Because the logic in sql server will take out some processing speed?

Very thankful and appreciate the help from you all. I really need the advise from all the expert, if anything is not clear please email me, i will try to explain it better. Thank

Your's sincerely
Ernest Wan