Its sounds like you already have a list of prospects, which is great. I'd take a day or two to determine if you can secure warm introductions from friends, acquaintances, advisors, etc into any of these target companies (LinkedIn is a stelar resource for finding these types of intros). If you can, then you should have a more receptive target which should help you gain some confidence in your own abilities prior to jumping right into the "cold calls".

Another technique that I've used with some success is to determine the target individual is within a company and try to find their preferred communication channel. For example, I've gotten some really great contacts by connecting with people first through Twitter or their blogs. I think this can sometimes cut through the noise of the 100 unsolicited calls they get in a day.

You may also want to try sorting your target list by those you think have the most strategic importance. Then, start calling from the bottom of that list (i.e. the folks who you believe have the least strategic importance) and work your way up. This will give you the opportunity to work out your pitch/confidence with some lower priority targets. I've seen some startups try to pitch their most important potential partners right out of the gate and have a bad experience because they haven't had a chance to refine their pitch yet.

As far as the message, being straight forward about what you want out of a meeting is definitely the way to go. Make sure that you also figure out what the benefit is for the potential target. For example, can you offer them some discount or free trial of your product in exchange for some feedback at this early stage. The actual benefit you can provide to them will obviously vary greatly depending on the type of product you are selling and the type of company you are selling to.

Hope this is helpful- good luck!