Karl,
It is possible to import TC3 content into 2009/10 (through "open for edit" in TC3 and "import" in 2009/10 is the easiest) but you will find that you may have to fix a good few of assets, this could be fairly time consuming (especially if you are not used to fixing content). Unless you are happy to do this then you might like to consider buying the TS2009 S&C add on as "the easy alternative".
Cheers
(PS - I'm NOT an Auran shareholder!!!!)