Um, VNC is not a Windows emulator. It's a remote management tool that allows you to view the desktop of a remote computer that's running a VNC server. A VNC server can run on other operating systems such as Mac OS X, Mac OS 9, Linux, and the BSDs. Even some hobbyist operating systems have versions of VNC that run on them. So this is not just limited to Windows.
No matter what VNC viewer you use, the experience you get from the remote computer running the VNC server is dependent on the speed of the network connection, especially because VNC redraws the entire screen. You can make it only redraw a section that the pointer is over, but that can get annoying. Really, the faster the throughput on the network when accessing the VNC server, the better your experience will be. The slower the connection, the choppier the experience will be.
Also, connecting a peripheral on your Mac and then accessing your remote computer through VNC will not make it accessible to that computer. VNC is only meant to be a way to remotely control another computer....nothing else. If you want that peripheral available to that remote computer, you'll have to connect it to that remote computer directly....no ways around it.
• Apple iMac G5 17" (2 GHz G5) - Mac OS X 10.5.8/Ubuntu 10.04
• Asus Eee PC 901 (1.6 GHz Atom N270) - Fedora 13
• Apple Macintosh Quadra 650 (33 MHz MC68040) - Mac OS 8.1
• "JHVH-1" (2 GHz AMD Athlon XP 2400+) - Slackware 13.1