I've been following this for a while on the Yahoo ASCOM group (seriously do they need sometimes 60 e-mails a day?).
The s/w upgrades ASCOM 5a to 5.5. It may instal saying its Release Candidate 7 - but I believe its the final version.
Available from the main ASCOM website.
http://download.ascom-standards.org/...m5.5Update.exe
Matt