Huge SQL Queries In SQL 2005

Good evening:

 We're porting an old app written in ASP.NET  1.1433 and SQL 2000 to ASP.NET 2.0 and SQL 2005.  In the old app we have a few data grids that are populated from a dataset pulled from the database.  We use a SQL query that we build based on more than 10 different user inputs, the result of which is an enormously complicated SQL string.  We'd like to move this processing into a SPROC in the 2005 database.

Rather than writing stored procedures to create the SQL SELECT statement, is it possible to pass an entire select state ment to a SPROC and have it executed within?  We're trying to capitalize on paging in 2005 using ...ROW_NUMBER() OVER (ORDER BY PM ASC)... and building the string using IF ELSE statements is mind numbling complex and tedious.

And suggestions woudl be great.

Thanks,

Brad