The XNA over VB barrier has finally been shattered - many thanks to Kalamus1 for his demonstration and for pointing me to a tremendous new resource by rm2kdev: http://www.xnatutor.com/
I still have a long road of learning ahead of me to fully understand and transition my older works to XNA, but I'm thinking that it will be a huge benefit to us all.
With GDI+ I was putting up with frame rates of around 22FPS - at super low resolution even - and many users were bogging down to around 1FPS... When Kalamus1 sent me my own tutorial source adapted to XNA, I totally freaked! My shoddy 22 FPS had exploded to nearly 4000FPS!
The next test was to run the project at full screen. It scaled up very nicely and was still blazing along at around 3000FPS.
Mind you, this was on my monster quad-core workhorse computer at work. The next test would be to execute the project on my older dual-core laptop, at home. The results were still a screaming 2400 FPS!
Keep in mind that most production games will be ticking along at significantly slower speeds. Playing World of Warcraft, for instance, I'm lucky to be getting between 25-35 FPS, and it's still smooth. People with souped up machines and high-end video cards might be enjoying between 60-120 FPS on modern games.
With that in mind, even 1000 FPS would be ridiculous. Of course, this should decline steeply as the complexity of our code routines grow, and in some instances we might even be forced to limit the FPS to a fixed rate, but at least we can shed the nagging concern that our apps may well give an abysmal performance on machines that may not have been as gutsy as the primary development environment.