added documentation about VT-x/AMD-V in virtualbox

README.md

@@ -43,7 +43,16 @@ Virtualbox can be downloaded from the oracle homepage using the URL
 http://www.oracle.com/technetwork/server-storage/virtualbox/downloads/index.html
 
 Be sure to install the version matching your host system regarding architecture
-and operating system. Also install the **Oracle VM VirtualBox Extension Pack** 
+and operating system. Also install the **Oracle VM VirtualBox Extension Pack**
+
+Since isochrone-vm utilizes a 64bit client OS it is important to check for two
+things:
+ - You'll need a 64bit CPU that supports VT-x/AMD-V hardware acceleration.
+   If you are either using a 32bit CPU or a CPU which does not support VT-x or
+   AMD-V isochrone-vm can not be used.
+ - You need to check that VT-x/AMD-V is enabled in your BIOS settings. For some
+   reason this is not the default setting for most systems, so be sure to check
+   your settings and to enable VT-x/AMD-V.
 
 ## Working with isochrone-vm
 Using isochrone-vm is pretty easy. All you have to do (after your system has