64bit driver connecting to 32bit SQL 2005

I need to know urgently if this is a supported implementation....

I have a 64bit application on a 64bit Windows 2008 R2 SP1 server. The app must use a 64bit driver.

My database is SQL server 2005 on a 32-bit Windows Server 2003 R2 SP2

Also I need to patch the SQL server 2005 from SP3 to SP4 - is that a straightforward patch?

Thanks