Hi Benne,
Welcome to the forum. With regards to your question, since you are looking to host the
website hostings you design for your clients, you can start off with a Reseller plan as you can create multiple accounts and manage them yourself and each
website hosting hosted under the reseller account gets it's own control panel.
ASP.NET Ajax extensions are installed on few of our servers.
Feel free to ask if you have any further queries.