The best advice. Trail both and then decide. I was a long time fan of VMWare, however recently moved to Parallels. Side by side, Parallels gave me a 5.1 experience index for Windows 7, and VMWare Fusion gave me a 4.9. Performance wise both are solid on my hardware, however I prefer the interface and coherence features of Parallels over Unity. This is however a personal preference. Full disclosure: I run a MacBook Pro i7, 8GB's of RAM and a 500GB 7200RPM HDD.
Both product does the job, and both work well. They are also in the same price bracket. You also can't compare features since both have the same functionality, just the method of implementation differs. The choice between the two is really up to you and how you use Windows virtualised. I game in Windows, and Parallels provided me a better experience. I also had issues running Expression Web, Silverlight and WPF in VMWare due to the graphics card, but this has apparently been resolved in the latest update.
My wife however prefers VMWare and finds it easier to use then Parallels. Moving machines between the two are fairly easy. Use one for the full trail, and then transfer your machine to the other and trial it. Do a comparison on which one works for you.
Perhaps it may be less hassle to build a clean, new XP image rather than import the Sony?
Have you tried using VMWare vCenter Converter? It's a free utility.
Check your Windows XP license string. If it's a OEM license string, don't attempt the following conversion.
From memory, these are the steps in using Converter:
Power on the Sony and connect to your network. Install Converter package on another Windows PC with the disk
capacity to hold your Sony disk image, launch Converter, allow it to install the Converter agent/service
software on the Sony. Begin conversion, you're storing the converted Sony disk image on the Converter
workstation.
From your Mac, map a drive to your Converter workstation, import the stored Sony disk image to either the Parallels or VMWare Mac client software.
When you start the disk image the first time on your Mac, you'll be required to supply the license string.
These aren't finely detailed steps, but you get the idea.
Best Answer
You can technically run Lion in a VM, but I really really really wouldn't recommend it. Here's why:
You're basically entering the murky world of Hackintoshes
Hackintoshes are inherently "hacky". The performance is rarely going to be as reliable as running OSX on mac hardware.
You're violating Apple's EULA.
If you really want to do it, here's a link, but I really think it's a fool's game.
Recommendation
You'd be better off just getting a Mac Mini or something and if you really want to run Windows natively, then remote desktop from Windows to your Mac mini. I'd recommend that.