As seen, Linux is getting a larger piece of the market like a free system for implementation of specific designed softwares. Commonly you can find stores running software designed for themselves on a linux platform. What does it means? Ok, you are thinking: what the hell is this guy saying? Think with me: is linux, free, isn't it? so, why will somebody pay for a OS if you can get a free one? That's the point! Developing directioned software in linux is getting common around the world!
Developing software for commerce automation in Windows is as easy as you can think, but there's a reason to discard this: you can't trust on a data base like MS-SQL server or other one like Access MDB's. They are not failsafe. You have data loss in a greater scale than you would imagine, like I saw once in a drugstore. Sometimes they got 100.00 US$ of difference in the checkout. So, why I'll pay almost a hundred bucks for something that I can't trust? Well, you can use linux! Maybe you will spend a lot of time developing an graphic interface, but you can offer a tool that you will not let you to the court! And you can dig the hole and get all those machines that are engraved, like 386's, 486's and others. Some Bill Gates' friends will say: but microsoft get you and your personal trained and you have garantees! But why a linux software developer can't give it too? They are very well rewarded, aren't they?
You can trust in C
Maybe C can be a difficult language to manipulate data, but today you have all the tools for implementation of the interface, like X libraries with all the modelling tool (windows, buttons, etc.). They're not visual tools, but a bit more work will not kill your neurons. And you can implement data exchange with SQL servers, like MySQL, PostgreSQL. As I mean, all of these tools are trustable. And remember: the compiller that are you using is free.
Start with a good planning. It won't hurt, trust me. Maybe applying a life cycle model could help a lot. Software Engineering for free software is discardable, but WE ARE NOT TALKING ABOUT FREE SOFTWARE!!! A good Requirement Analysis is a helpful tool to start planning the work and thinking what any department will need. In the checkout you may need a medium machine, like P54's or P55's (Pentium and Pentium MMX), but you can put a 486 as price consulter. One second more to the consumer will not be notable. And in the credit sector, maybe you will need a Pentium II. More robust machines will be the servers.
Interface needs are other point to meet. A price consulter can use a well designed text interface. Otherwise, at the checkouts you will need a good fashioned interface. Remember, interfaces are difficult to design, but a good presentation saves the day. It should be clean an informative. And can be a text one!!!
Experience in the Area
As I have seen all around, more institutions are adopting linux as a platform for developing tools. Banks, large stores, small stores, gas stations, are controlling cash and stock movement with software developed in free platforms. And they are happy with the choice, as the developers are. You can interact the SQL server of a bank with more transparency of what are you implementing than in a closed system. And any fail in the system can be found and corrected in less time. So, if there is a crescent demanding on this kind of system implementation, it should be good enougth to get the place!
Last word for the free software community
Yes! FREE SOFTWARE is what we are defending, but when you are developing a system on demand for a particular application, it could not be free! Or, you can design a system for free, but you can earn money on maintaining it. Ok, I love free software, but we live in a capitalist world and nobody could live without the green ones.
Last word about the application of older machines
The cost of an investment in newer machinery is very high, so people should use what they get in hand first, and then, acquire newer machinery in a gradative manner. Another point to get in mind: why are you investing 1,000.00 US$ in a machine that it's power of processing wont be useful in certains sectors, like pre-checkouts or price consulters? So let the old friends work together! And be sure that a 486 won't crash as a pentium. ;)