There probably is no “original key”; it appears the machine is oem with XP already installed. Such a copy of Windows, and any associated key, are not portable. Downloaded copies of XP can be installed, but this gets tricky. The downloadable keys created after initial release of XP were blacklisted in SP1, and so cannot be used. There were subsequent volume license keys leaked to the web which overcomes this. However, this also requires using a program which circumvents WGA phoning home for validation. If this technique is used, SP2 and SP3 can be subsequently installed, but only if downloaded as separate executables (that is, not if using Windows Update, as the volume license keys are now also blacklisted). If a machine has had a retail or corporate version of XP independently installed and WGA used to validate it, a hardware signature is created (not the MAC address) using a combination of components in the machine; this unique identification prevents installation on another machine unless pre-approved by Microsoft, including in a virtual machine. Security updates can be installed via Windows Update in the above scenarios, but not any other updates.
Being able to run Windows games in a virtual machine depends on the game, the amount of RAM that can be allocated to the guest OS, and to some extent the type of virtual machine and the cpu. Modern commercial graphics intensive games will be problematic without sufficient resources available to the virtual machine and its ability to utility those resources.
That still leaves the question of how many physical disks you have. In Windows, the term “drive” is very often used interchangeably with the term “volume” (which is a partition), but this is incorrect. There is no “C drive”, “D drive”, etc. - they are volumes. Your fdisk report shows the first partition to be 30GB out of a total 300GB. There is a second Windows partition, approx 210GB. Perhaps you are thinking C: and D: indicate two drives when they are actually partitions on the same physical disk?
Finally, the partitioning you have will not work. In addition to the two Windows partitions, there is an extended primary which is 58GB inside of which are three “logical” partitions. However, these are very small, not quite 1.5GB each. This is not enough space for installation, and that may be the problem which is stopping the installer.
If the above issues re XP are not a concern for you, my suggestion is to instruct the openSUSE installer to wipe the whole disk and create its own partitioning. If you wish to leave the XP partitions, in the installer use Expert Partitioning to delete the extended primary (and with it, the logicals inside) and then use that space for a new extended primary.