I used salesforce.com in my last company and liked it a lot. Lots of community activity for help and some very nice features. So of course when we needed a CRM for a new company I talked to them. The version you want is about $50 / month per user ($600 per year). With a sales force of 70 people, I gulped. And don't forget, no matter what you have, you have to spend a lot of quality time setting it up and training. Otherwise it's nothing more than a glorified contact manager.
I also remember using Sugarcrm in the past, so installed the free system on my hosted server. It was pretty ill behaved during installation (especially figuring out chmod access rights) but I got it installed. Took me a couple of days and some php tinkering. But a pretty sophisticated system when done. Problem was, when you run it, it's kind of a pig and pretty slow response time.
update: There is a new version of Sugarcrm. I hosted it on TMDhosting for $46 / year. And it's fast. They install it for you in an hour or two.
Then I found a derivative of sugarcrm called vTiger. Took me literally 5 minutes to install on a hosting site including setting up a MySql server instance. And it's fast. However you do lose even a little more functionality in some areas, but really nice modules for thunderbird, outlook, word and even a webform which automatically populates leads.
To save time and performance, do a web search of "web hosting sugarcrm" and you will find companies which will run (and even setup) your entire system for $70 a year, for all your users. And if then can run sugarcrm they can run vTiger.
But like I said, the big thing is setting up your system. No matter what your CRM, you have many business decisions to make. More on that later.