Just found this http://www.cloudshare.com/Products/CloudShare-Pro/CloudShare-Pro-overview.aspx and have been having a bit of a play with it. Lets you set up VM's like Win2k8, CentOS, SQL etc etc, up to 6 different machines at a time.
They beta is free at the mo and only requires email address to sign up. Have a look if it is your cup of tea.
J.