Been using Zoho CRM for three years now and its grown nicely with our company. A good level of integration with our other systems is provided and we can easily customize it to our needs. Found a few Nz based consultants for when we needed deeper customization. 

Also use their Zoho Support to run our little support servicedesk, again very easy to use. 

We priced up Dynamics and SalesForce.com initially and Zoho was massively cheaper. But as others have said above I'd highly recommend spending some time writing up your business requirements to make sure every feature you want can be properly implemented to avoid having to change CRMS later, and engage some external advice if you're unsure.