If you are looking for a CMS in .net , I will recommend you to go with mojoportal. You can find more details about it on
www.mojoportal.com
The main advantage with this cms is that you have many inbuilt features like forums , blogs and many more open source controls has been used and you can customize them as per your requirement and we can create our own web controls and use it in the cms.
The support given by mojoportal forums is quite good . Most of the queries get resolved by the topics already in their forum. There are few chances when you dont find the answer there. In that case you can directly write up to JOE, the author and creator of mojoportal, he is always there for mojoportal users.
This is just a suggestion , as i have been working on it for last few months.