Since the mac is sending the job over the network to the PC - it should be easy to tell if the mac has handed off the job to Windows by opening the console app on the mac (/Applications/Utilities).
If the PC accepts the job from the mac, then something should print even if you are using a generic printer driver.
Look at the error_log, access_log and page_log in /private/var/log/cups as you print.
The job should get:
- queued on the mac
- sent to the PC
- cleared from the mac queue
- queued on the PC
- sent to the printer
- cleared from the PC queue
You should be able to know if there is a problem on 1-3 using the console app on the mac. If there are errors, you can post them if they are not obvious to you how to react to them. I would guess you would have seen the jobs backing up on the dock or gotten an error dialog on the mac end if the problem were with your setup on the Mac.