I have used Parallels Desktop on my 20″ iMac since well before it was released, including most of the public beta versions. When they offered it for sale, I bought it without hesitation. In short, the software is much better than one would expect for the price.
One thing I must note about Parallels. Do not expect much if your system is RAM starved (ie, you have less than 768MB). Your poor mac will be paging to disk almost constantly and you’ll wonder why your blazing fast computer is so slow. That is because you are beating the tar out of your hard drive. Do yourself a favor. Spare your hard drive (and your precious data) by spending $160 for 2GB of RAM. I did this on my 20″ iMac and my MacBook and both scream.
I use Parallels for running three different operating systems, FreeBSD, Linux, and Windows XP. Since I develop software that runs on the first two, I regularly need access to them both so I am often running one of them in the background. I can code, rsync to the virtual server, test, and continue coding. I open SSH sessions to the virtual server just as if it were a real one. For nearly all intents and purposes, running these operating systems under Parallels is every bit as good as running them on a real server.
In some respects, it is quite a bit better. Since Parallels has come out, the dual 3.0GHz Xeon system that I have tucked away in a rack in our guest bedroom (because the fans are so loud) has not been powered up. In many ways, Parallels is much better than having a real server.
1. It uses far less power, dissipates far less heat, and generates almost no noise pollution which is quite nice in my Texas home.
2. Convenience. My dual Xeon is a server, so switching operating systems meant going into the other room, unplugging the active hotswap hard drive, and plugging in another. With Parallels, simply pause the running one, select another and start it up.
3. Portable. The dual Xeon is anchored to the rack in the closet. My virtual machines can be dropped onto my MacBook drive for portable access. I spent two months away from home this year and that feature was significantly better than dragging along another computer for testing.
4. Easy snapshots. I like to test my software on “virgin” boxes. This means reinstalling the OS quite frequently on a “real” server, or as I do on the Xeon, building a FreeBSD jail to test in. While the SATA disks in the iMac cannot keep pace with the Ultra320 SCSI disks in the server, I can generate a new system with a clean install simply by duplicating a Parallels disk image.
5. Leverages existing computing resources. I already have a really fast desktop, more than fast enough for development work and software testing.
6. More accessible. Because my virtual machines are so much faster (than Virtual PC on a dual G5), I use them much more frequently. Things I would have seldom have taken the time for such as, “I wonder what this looks like in IE for Windows” I check. There is value in that for developers.
7. Stability. My systems never crash. Anything that changes that makes me particularly grumpy. I have had only one crash while running a very early beta of Parallels. I stopped using it until the next beta came out and it’s been steady as a rock every since.
There are a couple downsides to using Parallels. For example, I could not run Virtual PC 2004 for Windows under XP when XP was running under Parallels.
You need enough RAM for Mac OS X (1GB min on Intel systems) and the operating system you will run. For most people, that will be XP which should have 512MB set aside for it.
Parallels is highly recommended.