The Switchvoice IP0x series or PR1 running the Switchfin GUI are very powerful and flexible.  There is nothing extra to buy on the PBX side as all CTI links would be done over the IP network it is connected to. However, it may require some unique code work if you are looking for something special in the way of database look-up upon incoming calls. 

In short; what you are asking for can be done and has been done. 

There are some off-the-shelf packages that will work with this product line and may give you what you need without custom work performed. 

The telephony engine under the hood is Asterisk, (as you probably already know).  Asterisk provides a conduit to external software called "The Asterisk Manager Interface" or AMI.  If you search the web including topics as "Asterisk compatible software" "CID software for Asterisk" "Asterisk incoming screen pops" and make sure when reading about what you find that it says it talks to Asterisk using "Asterisk Manager Interface" you are sure to find something that may fill your need at a very affordable investment or possible open sourced.  At the very least, most add-on packages offer a trial to test it so you can see how you like it.

Here's a small article related to your question:

http://www.coercs.com/2010/11/23/use-po … erisk-pbx/

Does this help?