Just a personal opinion here:
We have recently had a discussion regardinh Novell vs Windows for a network Operating system.
Personally, I would not recommend Wondows as it os high maintenance, if you don't have server experience or time, you are better off with NOvell s it requires a lot less attention one up and running (fire and forget solution!).
Now anyone that is an MCSE will recommend Microsoft and this will go in a circular fashion and no resolve your problem.
Note: those that will recommend MS will be trained MS techs, they find it easier as they have training and are accustomed to fixing things. I prefer Novell because when I was dumped into a NetAdmin position with no experience several years ago, I found it a piece of cake and I had a tonne of time to learn the system instead of needing to jump into it right away. I would recommend that if you but a NOvell operating system, that you do hire a professional Netware CNE to install the first time around, as with ANY new OS, but you will have NO problems maintaining it yourself, it's a piece of cake and one of the most secure, centrally managed systems available.
You should do your homework yourself though to decide what will work and what won't, I would suggest contacting someone who consults in several different systems to avoid a biased reponse, but as far as I'm concerned, jumping into Win Server will provide you with an instant full time position, if you want one.
WIth the Excel issues, I really think you should talk to a local ACT dealer or at least get some further Act training. Even if you need to export filtered data into Excell for someone else, you will save a lot of time and effort by using ACT across the network for Data entry as well as data storage. It is a great CRM once it is utilized properly. But to cross over like that is time consuming, risks data integrity and as you say, people can manipulate your records.
Spend the monet and get licences for all users and run ACT from the server. You can also look into a telephony server, Nortel AND NEC both make very high end telephony servers and unified messaging platforms that will even run MS exchange from your telephone server for tighter integration.
There are also several Key Telephone Systems that will give you ACT integration and offer predictive telephony dialling from a single database without duplicating calls but you need a single, centrally managed ACT database.
if you got to NEC's Network Groups website, you can find a dealer from the locator and at least open doors for your options and possible much cheaper and more robust solutions than Network Software offers.
Dealer Locator pages:
NEC: http://tinyurl.com/yskeb
Nortel (Business Communication Manager Telephony server): http://tinyurl.com/yohi
I just want you to realize you have many options other than just relying on network software to help you in a call center situation. They have never released any products that will out perform or offer more features than telephone manufacturers have.