You're entering into a pretty crowded field. There are tons & tons of monitoring tools out there. The only advice I can give you is that you need a hook, something that no one else has thought of. If you're just capturing standard performance metrics, what sets you apart from SQL Sentry, Confio Ignite, Idera Diagnostic Manager, Microsoft Operations Manager, Quest Foglight, Red Gate SQL Prompt... and those are just the ones I thought of off the top of my head. Wait until you do a google search on the topic.