My web Application is very slow

i have:

I reinstalled my servers because I bought new boxes.

1. Application server running windows 2008 r2 IIS

2. Database sever running windows 2008 r2  and Sql Server Standard R2

Users complain all the time that the application is pretty slow. I already checked the servers and they are ok, i checked the network and is ok. The odbc is well connected. The database was running on sql server 2005 before the change. Is there something I should do on the database? Im not a dba but please let me know what should I do.  Before the change users used to query  the database in 10 seconds , now it is about 2 minutes.  All the process of the appl are slow. The servers only run the role of appl and the other the role of database. 

thanks in advance

Ignacio Gómez