IMO You are going about this in the wrong direction!
In other words since you're totally new to virtualization starting with a loaded gun (creating a virtual machine of a know infected system) is a dangerous place to start. Since you have a new pristine computer I'd install the virtualization product of choice, create a new normal virtual machine using either Windows or Linux and then learn how to properly use the product. Once you have a handle on how the product works and what you can do with it then do a P2V (Physical to Virtual) of the infected system only if you have no the choice.
That said...
Unless you have an absolute need to have a virtual machine of the infected system I'd clean the system before doing the P2V and if it can't be cleaned then do not virtualize it as you playing with a loaded gun again. 
What would be more prudent and safer it to simply boot the infected system with a Live OS CD/DVD/USB Drive and make a Data Only Backup to external media. With it being Data Only and no Executables you would then scan the Data Store on the New System before migrating the Data to the system thus leaving the system clean and virus free.
Now if you really need to have a virtual machine of Windows XP then if you have the right version of Windows 7 you can have on for free from Microsoft, it's called Windows XP Mode. Then you're starting with a known good clean scenario, not transferring infected executables to a know good clean working system and you can leave the garbage behind! 
BTW Creating a new known good virtual machine, whether XP Mode or other, it will be a better scenario in the long run as P2V'ed virtual machines almost always have more issues to deal with and never see to preform as nice a a clean built one both in the begining and in the long run tend to be far less problematic too.