The first fundamental question is what office did you upgraded to it is 32 or 64 bit.
You should have toolbar (ribbon) with acrobat icons. If the icons are not created you should check whether add in is OK or suspended (Disabled). There is the access to Add ins on the Outlook menu.
I suggest you to read this link: What’s new in Microsoft Outlook 2010
And here you have the idea how to enable the Acrobat Add in the Office: PDFMaker Unavailable in Office 2007 and 2010
What I do, I simply select the emails I want to archive and click right button on the mouse than select “Convert to PDF” or “Append to PDF” it should do the work if Acrobat is present in your system.
If that is not enough let me know more what is the procedure that you apply before to convert the emails. I’m doing it on regular bases in my Outlook 2007 but I know that Outlook 2010 changed so that may need some adjustments.
Finally is you have the problem with enabling the Add in let me know I find the procedure for you if you can’t.