Helping people with computers... one answer at a time.
What you're looking for are called "Rules" in Outlook, and they're incredibly powerful. I have 33 of them defined.
Using it for multiple accounts is only the tip of the iceberg...
On the Tools menu, there should be an item there labeled Rules or Rules and Alerts. Rules allow you to have Outlook take various actions on email as it arrives, depending on a host of conditions about that email.
In your case, it's quite simple to have a rule that says "If email is received on this account automatically move it to that folder."
Most of the rules I use help coordinate my incoming mail in various ways, including:
But even my usage only scratches the surface. Spend a few minutes examining the options that are available as you define a new rule, and you'll see what I mean.
Outlook Express has rules as well, but a much more limited form. Other email applications often have similar concepts, with varying degrees of functionality.
For organizing the incoming flood of email, A good set of rules is hard to beat.