How to know if a database is not available

Hi I need to create a SP with the following fake code:
(Sql Server 2005)
....
If DB1 is available and DB2 is available
Insert into DB3
Select field1, field2 from DB1

Insert into DB3
Select field1, field2 from DB2
Where status = 1
Else
Insert into DB3
Select 'One of databases is not available','0'
End

What I need is to know if a database is Restoring.. or Offline...

Thanks in advanced