Parallels sell virtualisation software including Parallels Workstation - a product similar to VMware Workstation. It was suggested to me that I try out Parallels Workstation as apparently its VT-using capabilities give it the edge over VMware in terms of speed.
I had previously heard (from the mouth of a VMware employee) that VT does not allow greater speed of virtualisation - it only makes it easier to implement. Certainly, I noticed no subjective difference in speed when running VMware Workstation with VT disabled then enabled. Parallels, however, claim that VT can make virtualisation more ‘efficient’ - which implies ‘faster’ to me.
Installation of Parallels Workstation was similar to that of VMware Workstation - no reboot required, a virtual network adapter installed, etc. The interface is quite similar to that of VMware Workstation, too.
I started my first test - installing XP with SP2 on XP with SP2. This didn’t go entirely smoothly: the installation routine stalled at ‘Initializing devices’, with the progress bar at around 100%. I powered off the machine, bumped the RAM up to 512M (can’t hurt but was probably irrelevant) and removed the sound and USB controllers, then restarted it. XP’s setup continued from the start of the ‘Initializing device’s phase and completed without problems.
The installation, including the brief pause to switch hardware and joining a domain, took around 45m in total on a Pentium D 940 with 2G RAM and the virtual machine files on an otherwise-idle 7200RPM IDE drive.
I installed the guest tools (this, again, is similar to the process with VMware), shut down the guest OS, enabled the sound controller, booted the guest, checked it didn’t crash, then did the same with the USB controller. When I plugged a USB device in for the first time, the host OS asked me to install a Parallels USB driver. One thing to note: None of the Parallels drivers seem to have passed Windows logo testing. This worries me slightly, as the last time I used drivers with the same issue, I had horrible problems (thanks Terratec).
Speed seems a little faster than VMware - at least in terms of responsiveness, but this is quite subjective. One thing I am sure of, though: if the Mac version of the product is this good, running Windows inside OS X must be pretty painless.
I wouldn’t use Parallels for application testing just yet, as it doesn’t have the essential multiple snapshot feature of VMware, but for day to day use, it’s an alternative worth considering - especially as the price is half that of VMware Workstation. There’s one other option, though: Microsoft Virtual PC is now free. I don’t think Parallels can compete with that, except on Mac OS.