Yes, there is a workaround.
The problem
Parallels does not support the retina display yet. I have no idea why the company has announced that it now supports it. Parallels is simply not giving Windows access to the increased DPI. As you can do this yourself quite easily, I guess they were pressed for time.
Running on the Retina Macbook Pro makes Parallels and Windows look worse rather than better. As the 2 by 2 pixels compatibility mode of the Retina display creates very sharp (jaggy) pixels compared to a regular display, Apple does some blurring in the upscaling. This makes text very blurry and is very hard on your eyes.
The solution
The correct solution is for Parallels to give Windows native resolution and use the DPI setting in Windows 7 or Windows 8. This is rather simple using Apples APIs for most programs, but as Parallels dealing with graphics is anything but bread and butter code, things probably becomes trickier. For most programs, you simply announce that you are Retina compatible and you're given the full resolution. You can forgive Parallels for not having had the time to add Retina support, but it is not acceptable to issue a press release to say you have. This tricks us into buying a product under false pretense.
The workaround
There is a way to run Retina Windows using Parallels (with manual switching and no coherence, which is very annoying). The way to get high DPI windows today is to manually switch resolution between 2880x1800 (Windows) and one of the scaled settings (Mac) when you move your eyes or desktop between Windows and OSX. Download one of the free programs to do this (for example FreeRez). It will allow you to set native resolution which allow Windows to be as good at Retina as is the Mac. Don't forget to set the DPI in the Windows display settings (right click on desktop and choose "Screen resolution"). This is called "Make text and other items larger or smaller". 200% is a good default setting (personally I use 150%, but I like a lot of room). By automating the resolution switching process, you can make the switch with a single keystroke.
The good news
The good news is that Windows looks great in Retina mode. Super sharp!
Last edited: Jul 17, 2012