I was all set to use David's solution too, but either I'm doing it wrong or it doesn't work with current versions of the applications in question.
I have a new laptop with Windows 7 64bit and I'm trying to use WLM. The old machine is XP SP3 with Outlook 2010. I've copied the PST file over from the old machine and installed the current version of MailStore Home. However, when I open MSH, click Archive, choose Outlook, then select PST file, I get "Direct PST file archiving is not available in MailStore Home." It goes on to say that's only supported in MailStore Server, which is a $190 product.
So I tried Plan B - download OE6 to install on the old machine, with the intent of exporting from Outlook to OE, then copy over all the DBX files to the new machine for import to WLM. This has become so convoluted now that I can't even accurately describe why that didn't work.
MS, if this is how you expect people to "upgrade" to your new products, this is not the way to go about it.
Please, does anyone have any ideas?