Alpha Five is a powerful database and Web applications server and development environment that has been around for many years and continues to get more powerful but not at the expense of ease of use.
We tested Alpha 5 v10 on a Windows XP running SP2 in February 2010.
There are numerous tutorials, along with documentation, copious code examples and videos:
Alpha Five v10
70 Blanchard Road, Burlington, MA 01803
Prices: Developer $349
Application Server $599, both for $799
Unlimited Runtime licenses $599
Windows XP or later required with at least IE v7 or Firefox 3.0