Dedicated XP laptop, or virtual machine in a quad core desktop?

Unix

I have these softwares that require Windows XP: a Greek vocabulary software (audio), a Swedish dictionary (one language), Pradis (in which I have just the NIVAC Jn -volume), and Logos 3/Libronix.

What would be better? To buy a used laptop dedicated for this, with Windows XP? Or to install XP or Vista in a quad core desktop with a virtual machine (I installed Oracle VM VirtualBox about three months ago but couldn't get the XP installation to start (haven't tried updating Oracle yet), I have not yet tried Vista in Oracle. Have not tried VMware Player on this computer yet)? You can see the specs of the latter machine in my signature. Later on, before any of the drives fail, I plan to change the second drive in the desktop computer (the drive on which Logos is installed) to an SSD, and the first drive (on which I have Windows) to a hybrid drive. (The monitor is 1280*1024 pixel, it does support bigger monitors but I haven't afforded. Right now a big monitor would cost $41 - but I don't think it's the right time to buy a monitor right now unless I would be able to borrow some money for that over here without interest.)
The specs of the laptop are: Pentium 4 1.8 GHz single core, 512 MB RAM, DVD/CD, bag. I could possibly try bidding $5½ lower as the ad is a month old. I don't know about the size or shape of the HDD or battery but usually if they are really bad/tiny it says in the ad. The HDD is probably no more than 40 GB though.

Regarding speed, I suppose the XP laptop would be faster thanks to the CPU, at least until I would change drives in the desktop.
Pic of the laptop:

The major advantage of the laptop would be that I could easily carry it between my rooms. But the advantage of the desktop would be that in addition to my own L3 account I could install the spare (extra) Logos account with Logos 4.6c (the last version of L4) as well. Not all the softwares would work in Vista, the Swedish dictionary would work, but I would not try installing Pradis.
(Tomorrow, Sunday, I'm buying a colour laser printer cheap, $41, drivers that are tested to work with Windows 7 are available on the webpage. Since before I have a colour inkjet with scanner for which I have the XP drivers on a CD, and extra ink. I don't know/haven't checked the driver availability for either printer for other operative systems.)