Event Notification/Messaging Engine for Large Asp.net Web Application

Question

Hi
I am working on a web application which is a sort of bidding portal where buyer post their jobs and the service provider bid against them. The application is being developed using EF 4.0 , .Net 4.0 and Sql Server 2008. Now there are a lot of notifications that needs to be generated and send to respective parties/users. Some example of events are: if a job is cancelled, or a bid has been selected or a message has been posted on the job by the service provider and etc. Altogether there are 14 such events.
Now what my requirement is to be able to send an email , a sms to the respective parties. Also the logged in user should be able to view these notifications through a webform when logged in.
The application demands that no notification should be missed, hence i am looking for a scalable and reliable solution here. I am explorig MSMQ and sql service broker for managing a queue for these messages/notifications but i am not exactly sure if i am following the right direction. Also i would like to consider factors such as transaction management , uptime and scalability etc. I would appreciate any help in this regard.
Thanks & Regards
Sana