Putting as much logic as possible into the server component is definitely the way to go.
I did something similar, I would send the version as well as the md5sum of the executable.
Aside from being able to tell the 32 and 64-bit versions apart, the other advantage was that I'd be able to track whether they were running an executable with the md5sum I shipped, or if it had been hacked. Add that to an ip geolocation server, and now I've got a map of who is using a legal version and who is using an illegal version. I even plotted the success and spread of different cracks over time.. in our case, the Russian cracks usually lagged the Chinese cracks, but then had a better distribution network. Our auto-update function would check once a day on startup, based on the same version string and md5sum of the last check. So, we could see the person creating the hack.. same IP address, same version string, multiple md5sums, and their final md5sum would spread.
I also added the demo status and a unique machine id, and that let us answer questions like "Do paying customers ever install a hacked version?", "Do people who start with the hacked version ever pay?", "Into what languages should I translate my software", "How many demo users are in our funnel", "How long does it take a demo user to convert to paid", etc.
I did something similar, I would send the version as well as the md5sum of the executable.
Aside from being able to tell the 32 and 64-bit versions apart, the other advantage was that I'd be able to track whether they were running an executable with the md5sum I shipped, or if it had been hacked. Add that to an ip geolocation server, and now I've got a map of who is using a legal version and who is using an illegal version. I even plotted the success and spread of different cracks over time.. in our case, the Russian cracks usually lagged the Chinese cracks, but then had a better distribution network. Our auto-update function would check once a day on startup, based on the same version string and md5sum of the last check. So, we could see the person creating the hack.. same IP address, same version string, multiple md5sums, and their final md5sum would spread.
I also added the demo status and a unique machine id, and that let us answer questions like "Do paying customers ever install a hacked version?", "Do people who start with the hacked version ever pay?", "Into what languages should I translate my software", "How many demo users are in our funnel", "How long does it take a demo user to convert to paid", etc.