NT vs Unix Performance HELP!

Anyone have any experience running Online Workgroup Server on both NT and Unix (on Intel) and have any comparisons they would like to share? I have several customers running Informix SE on AIX and would like to move them to a PC platform (I don't necessarily think this is the best route but everyone is convinced that they can run everything on PC's and if I don't move them to PC's someone will come in and do it for me.) I'm talking large databases of 200-300 tables some as big as 17-20 million records of 300-400 bytes per record with 9-10 indexes. Largest customer only has 30 users. I would like to get some good responses with pros and cons from either solution. Does anyone else feel the same way that I do that PC's and NT are not necessarily the best way to go (I'm not knocking NT, I like the product, I have an NT Server and 2 IBM RS/6000's) but as an industry are being forced into it based upon what executives read in magazines and hear from their neighbors? Why does everything have to be graphical when a character based app runs well and does the job perfectly and fast? I still like my AIX boxes that run for 100-200 days without being rebooted and never require maintainance. I feel this is a great solution for my small-medium size customers that do not have a sysadmin on staff and I administer their system remotely including their databases. My easiest solution would be to load SCO on a big multiprocessor Pentium II machine and move my 4GL code over. The customer thinks the best thing to do is run NT and have a graphical front end running on a Windows based PC. Is the customer always right. Any comments and ideas would be great, I would love to share some of this information with current customers and (maybe) some future ones. Thanks, Randy