Ver 4.10 ODBC

I am using Informix Online 4.10. My question is: What is the preferred method for connecting to this engine via a PC based Windows C program? I will only be running queries against the Informix database (no updates). I would like to be able to use some form of ESQL in my C code to run these queries. Ideally it would be nice if there was a solution which was entirely PC based, I.E. nothing has to be run on the Informix side. I know that the updated versions of Informix have the ODBC drivers built in, but I don't think my client will want to upgrade at this point. Has anyone run queries from a PC against Online 4.10 and if so, how is the speed? Right now my application ties into the Informix box using an RS-232 link to a terminal server. I then issue commands to run ace programs from the PC by sending data to the Unix shell through the serial line. My PC based program then captures the results from the ACE program, parses the data and displays it on a windows screen. This solution works fine, but it is a pain to configure for each user. I really want to migrate to a TCP/IP ODBC type of solution but I'm not sure what components I need. Thanks for any replies.