database for dummy's!

Please, somebody help me, my head is spinning that much its about to drop off!

I am confuzed with a whole day spent trying to find software to what i consider a very very simple task. And all i can find is hundreds of articals telling me how nice and user friendly and custimizable and intergrational various software is, but not the detail of what it does!

In Brief, i am a very small company, 3 of us. I run 4 internet business's from one office, and we are growing. This is the software i need

I want to store address of my customers and potential new customers, kept in seperate files for my 4 seperate business's. I want to have a window on my pc so when a customer rings, i want to identify them quickly on screen, and type there requests there, such as more sale lit, point of sale material, but not orders, they go through the wedsites.

I also want to mail out a letter to 100 new potenial customers, a week with a free sample of my product. So i need to draft out a letter and mail merge this with a batch of my collected names and address.

Thats basically it! It would be nice to add things to each customer such as new product sample sent and on what date etc.

I do not want to mix these up with my contacts on my pc, such as my local plumber and hair dresser!

So what is this software called, is it contact managment, database managment?? I need it real easy as i struggle with pc stuff hence the dummies bit. I know a spread sheet can do this, but its to complicated, clucky to do the mail merge etc. shorly there is a nice and easy,program out there that i can use, i dont mind paying for it.

I run windows server 2003, and a mixture of win XP pro and win 2007 pro.
Thanks for your help