You Can Run the Platform Preview in Conjunction with Earlier IE Versions
A common concern that some developers have is the possibility of blowing away their current version of an installed software program when they test a new build. Fortunately, this is not the case with Internet Explorer 10. As you can see in Figure 2, IE 8 and IE 10 are able to coexist peacefully on my Windows 7 system.
Figure 2 IE8 and IE10, side-by-side