Microsoft has [posted a reminder][1] for those brave souls that are still using Windows Vista Beta 2, RC1, and RC2 -- it's time to upgrade to the final version. On May 31 pre-release versions of Windows Vista will expire. After that time the pre-release versions will reboot every two hours.

If you're still using one of the early version Microsoft will send notifications reminding you to upgrade starting May 18.

The upgrade process is a bit convoluted but a [handy table on the Microsoft bulletin][1] breaks down your options. 

Users of Beta 2 will need to do a clean install regardless of the final release version they decide to use. 

Those with Windows RC1 have the option to upgrade in place provided they upgrade to Vista Ultimate.

Curiously, users of RC2 must also do a clean install. Microsoft doesn't appear offer any comment on why the upgrade in place option is available to RC1 users and not RC2.

Pricing for Windows Vista Upgrades [range from $100 - $260][2] depending on the version you choose.

[1]: http://www.microsoft.com/windows/products/windowsvista/preview.mspx "Windows Vista: Beta 2, RC1, and RC2 Set to Expire"
[2]: http://www.windowsmarketplace.com/content.aspx?ctId=390 "Buy and Download Windows Vista Upgrades"