"... If I buy Outlook will it import the OE .dbx files....."
As far as I know, it can't be done in the latest versions of Outlook.
Anyhow, there's no need to waste your money on an expensive business-grade product such as Outlook because Microsoft's "Windows Live Mail" is free and is the direct replacement for the now-obsolete Outlook Express.
WLM will happily import all your old OE messages from saved DBX files. If you get stuck then post back when your new PC arrives.