Guys,
Don't know if this will help or further confuse. I have had an 0404 PCI card and a 1616m with microdock that I used with a laptop, then transferred the 1616m card over to my desktop using a PCMCIA adapter card. I started with XP32, then again with XP64 and used it that way for a long time with zero issues by making sure all my Windows files were up to date and all the drivers were also up to date for ALL my devices. The PCMCIA card from EMU eventually died, so I replaced it with a 1616 PCI card and still use my Microdock with it with zero issues. I do not, however, enable my onboard soundcard on the desktop, so there are not any conflicts. All Windows apps <media player, IE, etc.> use my EMU when SONAR is not also enabled. Just be sure to uncheck "share drivers with other programs". Use the ASIO drivers in SONAR and make sure your Patchmix settings match your SONAR project bit depth and resolution settings, otherwise, you WILL get BSD's and/or driver corruptions which are a headache, but you can easily fix them by immediately going to Device Manager and uninstalling your sound card, then going back up top of device manager, telling it to scan your computer for new devices and let the drivers reinstall, and then reboot. You should be good to go.
I use the EMU site's latest X64 bit drivers (beta) and Patchmix downloads and they haven't given me any problems. I mainly use SONAR x32 so I can make use of all my plugins without issues, but also have X64 installed for final mix/mastering once I've completed the project in X32. No problems or worries, other than you will likely want to save your DSP Patchmix settings in a separate folder so they don't get overwritten every time you have to rereun setup. Just load your 16 bit Patchmix settings for startup and then switch to a dedicated template for SONAR and you should be good to go. Hope this helps!!
PS Yes, I'm a computer guy by trade. It helps...:))