This is a very commonly reported problem with 2007, especially with a back end accessed thru a network. I'm assuming that with 800,000 records that this is probably your situation.
Make sure you have all of the service packs/hotfixes installed for 2007. Many of these slowness problems are reportedly fixed by these.
The Missinglinq
Richmond, Virginia
There's ALWAYS more than one way to skin a cat!