Slaving that HDD in a working PC and then copy the files with an extension *.DBX (OE store folders) and *.WAB (address book).
Gloing there through DOS is nearly impossible and the location varies.
Hope this helps as it is the safest way to do it.
I can't access my old computer(Win 98). Could someone please access your Outlook Express and click: Tools; Options; Maintenance Tab; Store folder and tell me the path you see (where 'personal message store is located'). This should help me find the folder I neeed on my backup CD to import my OE folders and messages.