Through WinXP I'd been using the old Corel WordPerfect 7 Address Book software (although I didn't use Corel WordPerfect any longer). I'd invested many years in the data contained in this Address Book, and although it wasn't all that "powerful" or modern, I had many hundreds of entries and a number of sub-books.
When I upgraded to Windows 7 and discovered WordPerfect 7 would not install or behave properly (even I tried to just manually run the previously installed Address Book component), I was forced to look for another Windows 7-compatible product. I also needed a way to migrate from Corel's Address Book to any new product's database, and hoped that my manual effort in this migration would be minimal although I was prepared to invest whatever time it took.
After exploring a number of products, I ultimately settled on StatTrak's Address Manager Business Edition v4.2
(not free, but $50 is reasonable) to meet my needs and provide all kinds of new functionality I'd never had before.
I was luckily able to export my Corel Address Book software into a CSV file format, though it wasn't perfect. I did a bunch of manual editing on it before eventually importing it into StatTrak's Address Manager. However because of the 1-dimension "flat" nature of the exported CSV data, it also reflected this 1-dimension "flat" characteristic when imported into the StatTrak product... rather than the "sub-book" 2-dimensional implementation I'd developed with the Corel product.
So I invested another week or so, manually reconstructing what I'd imported into the StatTrak product to organize things using the new enhanced capabilities and user-interface. The raw data was there from the import, but it needed to be re-located and re-organized in order to maximize usability per my needs.
After more than a year of using this new product (following a decade using the Corel Address Book, so it was really some separation anxiety for a while) I'm very satisfied with the results. I do feel the GUI of the StatTrak product could use some improvement and have written them about it (to no avail yet, though they did respond politely).
However as far as being a "contacts" or "Address Book" product I feel this one is excellent. I opted for the "business edition" because there were features in that version which I absolutely had to have and which were not in the "personal edition".
Now that you've mentioned the Windows 7 Contacts feature I've just done a little exploring. Interesting. And free.
But I prefer the 2-level organizational address book/sub-book -> individuals presentation of the StatTrak product. Very intuitive and easy-to-understand and use.